.  .    LIBRARY    .  . 

Connecticut 
Agricultural  College. 

VOL...     J)....b.4..1 _..... 

CLASS    NO ■rf....-A...>f. 

COST    . ^....9^....-^:.: 

DATE ._*..   A „19.:... 


Digitized  by  the  Internet  Archive 

in  2009  with  funding  from 

Boston  Library  Consortium  IVIember  Libraries 


http://www.archive.org/details/pseudoceratitesoOOhyat 


DEPARTMENT   OF   THE    INTERIOR 


MONOGRAPHS 


OF  THE 


United  States  Geologtcal  Survey 


VOLUME    XLIV 


WASHINGTON 

GOVERXMENT     PRINTING     OFFICE 
1903 


UNITED  STATES  GEOLOGICAL  SURVEY 

CHARLES   I).  WALCOTT,  DIRECTOR 


PSEUDOCERATITES  OF  THE  CRETACEOUS 


BY 


^^Ll^ECETJS    HY^TT 


Edited  by  T.  W.  STANTON 


WASHINGTON 

GOVERNMENT     PRINTING     OFFICE 
1903 


^i.il 


CONTENTS 


Page. 

Editor's  preface ^'■ 

Cla,ssified  list  of  families,  genera,  and  species 15 

Table  of  horizons ^^ 

General  remarks 1" 

Systematic  descriptions -'^ 

Mammitida ■ -'^ 

Mojsisovicsiidfe '"'^ 

Buohiceratid:e -*> 

Pseudotissotiida'  •^'^ 

Tissotiidfe "^1 

Sphenodiscida? ■^** 

Eulophoceratidw 83 

Coilopoceratidfe ^^ 

Cosmoceratida I'^l 

Mantelliceratida ^'^^ 

Mantelliceratidfe 105 

Metoicoceratid?e 115 

Heinziidfe 1^8 

Palchelliid:e l'^6 

Kuemiceratidse 1" 

Engonoceratidfe 153 

Placenticeratidie 1^8 

Bibliography -"'" 

Plates 251 

Index ■^■^7 

5 


ILLUSTRATIONS 


Plate  1.  Figs.  1-3. 

4-9. 

10-14. 

15. 

II.  Figs.  1-3. 

4-6. 

7-11. 

III.  Figs.  1-6. 

7-15. 

IV.  Figs.  1, 2. 
V.  Figs.  1-3. 

4. 

XI.  Figs.  1, 2. 

3,4. 

5. 

6. 

VII.  Figs.  1,2. 

VIII.  Figs.  1,  2. 

3-7. 

IX.  Figs.  1-6. 

7-9. 

10. 

11-13. 

X.  Figs.  1-4. 

5-21. 

XI.  Figs.      1. 

2-6a. 

7-24. 

XII.  Figs.  1-3. 

4-6. 

7. 

8. 

XIII.  Figs.  1,  2. 

3-5. 


Page. 


254 


Mojsisovicsia  durfeldi    Steinmann 
Buchicera.s  bilobatum  Hyatt 
Roemeroceras  syriaciforme  Hyatt 
Roemeroeeras  attenuatum  (Hyatt) 
Roemeroceras  gabbi  Hyatt  1 

Roemeroceras  subplanum  Hyatt     [ 256 

Paratissotia  serrata  (Hyatt)  J 

Paratissotia  regularis  Hyatt  i 

Sphenodiscus  pleurisepta  (Conrad)  / 
Sphenodiscus  pleurisepta  (Conrad) 
Sphenodiscus  pleurisepta  (Conrad)i 
Sphenodiscus  stantoni  Hyatt  J 

Sphenodiscus  lobatus  (Tuomey) 
Sphenodiscus  beecheri  Hyatt 
Sphenodiscus  stantoni  Hyatt 
Sphenodiscus  pleurisepta  (Conrad) 

Sphenodiscus  lobatus  (Tuomey) 266 

Sphenodiscus  lenticularis  (Owen)  i 

Sphenodiscus  lenticularis  var.  splendens  Hyatt  ' 

Sphenodiscus  lenticularis  (Owen) 

Sphenodiscus  lenticularis  var.  mississippiensis  Hyatt 

Sphenodiscus  beecheri  Hyatt 

Sphenodiscus  lobatus  (Tuomey) 

Coilopoceras  noviniexicanum  Hyatti 


258 
260 
262 

264 


268 


270 


Coilopoceras  colleti  Hyatt 
Coilopoceras  colleti  Hyatt 
Eulophoceras  natalense  H>att 
Metoicoceras  svvallovi  (Shumard 
Coilopoceras  springeri  Hyatt 
Aconeceras  nisum  (d'OrVjigny) 
Coilopoceras  grossouvrei  Hyatt 
Sphenodiscus  konincki  Hyatt 
Metoicoceras  swallovi  (Shumard )i 
Metoicoceras  whitei  Hyatt 


r- 


/■ 


274 


276 


278 


8 


ILLUSTRATIONS. 


Page. 


L.rrE  XIV. 

Figs.  1-10. 

11-14. 

15. 

16. 

XV. 

Figs.     1-4. 

5-8. 

9-11. 

12-18. 

19-20. 

XVI. 

Figs.    1-3. 

4-8. 

9,10. 

11-14. 

15-18. 

19. 

XVII. 

Figs.    1-5. 

G-S. 

9-12. 

13-15. 

16-20. 

XVIII. 

Figs.     1-3. 

4,5. 

6-9. 

XIX. 

Figs.     1-6. 

7-14. 

1.5-17. 

XX. 

Figs.     1-5. 

6-13. 

XXI. 

Figs.         1. 

2-6. 

XXII. 

Figs.     1-5. 

6-10. 

XXIII. 

Figs.    1-6. 

7-9. 

XXIV. 

Figs.     1-5. 

6-8. 

XXV. 

Figs.     1-4. 

.5-9. 

XXVI. 

Figs.     1-4. 

5-7. 

8. 

XXVII. 

Figs.     1,2. 

.3-14. 

15-17. 

XXVIII. 

Figs.     1-6. 

280 


282 


284 


86 


Metoicoceras  whitei  Hyatt 

Metoicoceras  acceleratum  Hyatt 

Metoicoceras  whitei  Hyatt 

Vascoceras  hartti  Hyatt 

Metoicoceras  swallovi  (Shumard 

Metoicoceras  gibbosum  Hyatt 

Metoicoceras  kanabense  Hyatt 

Heinzia  matura  Hyatt 

Heinzia  provincialis  (d'Orbigny) 

Heinzia  provineialis  (d'Orbigny) 

Knemiceras  syriacum  (von  Buch) 

Knemiceras  compreasum  Hyatt 

Knemiceras  compressum  var.  subcompressuiii 

Knemiceras  compressum  Hyatt 

Knemiceras  compressum  var.  suVx-omiiressum 

Sabpulchellia  castellanensis  Hyatt 

Nicklesia  dumagiana  Hyatt 

Pulchellia  compressissima  (d'Orbigny) 

Knemiceras  attenuatum  (Hyatt) 

Protengonoceras  gabbi  (Bohm) 

Knemiceras  gabbi  Hyatt  "l 

Engonoceras  belviderense  (Cragin)  > 288 

Protengonoceras  planum  Hyatt         J 
Engonoceras  uddeni  (Cragin)  1 

Engonoceras  serpentinum  (Cragin)  \ 290 

Engonoceras  retardum  Hyatt  J 

Engonoceras  serpentinum  (Cragin)    -i 
Engonoceras  pierdenale  (von  Buch)  I 
Engonoceras  pierdenale  var.  commune  Hyatf 
Engonoceras  subjectum  Hyatt 
Engonoceras  subjectum  Hyatt  i 
Engonoceras  gibbosum  Hyatt  / 
Engonoceras  gibbosum  Hyatti 
Engonoceras  stolleyi  Bohm      ' 
Engonoceras  stolleyi  Bohm  i 

Engonoceras  complicatum  Hyatti 
Neolobite.s  choffati  Hyatt  \ 

Metengonoceras  inscriptum  Hyatti 
Metengonoceras  inscriptum  Hyatfl 

Metengonoceras  ambiguum  Hyatt  > 

Metengonoceras  acutum  Hyatt       J 
Metengonoceras  acutum  Hyatt       1 

Metengonoceras  dumbli  (Cragin)  \ 

Placenticeras  syrtale  (Morton)       J 
Placenticeras  syrtale  ( Morton) 


292 


294 


296 


298 


300 


302 


304 


306 


W8 


ILLUSTRATIONS.  9 

Page. 
Plate  XXIX.  Figs.  1-4.  Plaeenticeras?  guadaluiue  ( Roeuier)  .310 

XXX.  Figs.  1-3.  Placenticeras  t-ancarlosense  Hyatt 312 

XXXI.  Figs.  1,2.  Placenticeras  sancarlosense  Hvatti 

3-5.  Placenticeras  newberryi  Hyatt      I 

XXXII.  Placenticera.s  sancarlosen.se  var.  pseudosyrtale  Hyatt 316 

XXXIII.  Figs.      1.  Placenticeras  sancarlosense  var.  nseuilosvrtale  H\attL 

'                                           31S 
2-4.  Placenticeras  planum  Hyatt  ' 

XXXn'.  Figs.  1-3.  Placenticeras  planum  Hyatt 320 

XXXV.  Figs.  1,  2.  Placenticeras  intercalare  Meek 322 

XXXVI.  Figs.  1-5.  Placenticeras  intercalare  Meek 324 

XXXVII.  Figs.  1-4.  Placenticeras  intercalare  Meek 326 

XXXVIII.  FiiTs.      1.  Placenticeras  intercalare  Meek  i 

[  308 

2.  Placenticeras  intercalare  var.  costatuni  HyattI 

XXXIX.  Figs.  1,2.  Placenticeras  intercalare  var.  costatuni  Hvatti 

/■                                                        3*^0 
3-6.  Placenticeras  placenta  (DeKay )  I ^ 

XL.  Figs.  1,2.  Placenticeras  placenta  (DeKav)  1 

33*^ 
3-7.  Placenticeras  stantoni  var.  belli  Hyatt ' " 

XLI.  Figs.  1-7.  Placenticeras  stantoni  var.  belli  Hyatt 334 

XLII.  Figs.  1,  2.  Placenticeras  stantoni  var.  bolli  Hyatt 330 

XLIII.  Figs.  1, 2.  Placenticeras  stantoni  var.  bolli  Hvatt-i 

"1  '  J "  s 

.3-1 1 .  Placenticeras  pseudoplacenta  Hyatt       ' 

XLI V.  Figs.  1-3.  Placenticeras  pseudoplacenta  Hyatt 340 

XLV.  Figs.  1,  2.  Placenticeras  pseudoplacenta  var.  occidentale  Hyatti 

.3-16.  Placenticeras  whittieldi  Hyatt  / 

XLVI.   Figs.  1,  2.  Placenticeras  whitfieldi  Hyatt .344 

XLVII.  Figs.  1—1.  Placenticeras  whitfieldi  Hyatt  I 

5.  Placenticeras  whitfieldi  var.  tuberculatum  Hyatt  j- 346 

6-8.  Placenticeras  spillmani  Hyatt 


EDITOR'S   PREFACE. 


Soon  after  Professor  Hyatt's  lamented  death,  January  15,  1902,  it 
was  the  writei''s  sad  duty,  as  a  representative  of  the  United  States  Geo- 
ological  Survey,  to  examine  all  the  paleontological  collections  and  manu- 
scripts in  Professor  Hyatt's  house  in  Cambridg-e,  in  order  to  take  possession 
of  those  belonging  to  the  Survey.  The  manuscript  of  the  present  volume 
was  on  his  desk  and  contains  the  results  of  his  last  work,  in  which  he  was 
actively  engaged  on  the  day  of  his  death.  Fortunately  it  was  almost 
readv  for  the  printer,  and  although  the  careful  reading  of  the  manuscript 
to  determine  the  author's  exact  meaning  and  intentions  has  consumed  con- 
siderable time,  the  changes,  either  in  arrangement  or  in  wording,  and  the 
additions  that  have  been  found  necessary  are  very  few  indeed.  These 
changes  are  all  indicated  in  their  proper  places  by  footnotes  or  bracketed 
statements  signed  b}'  the  editor's  initials,  except  the  unimportant  verbal 
change  of  "Cretacic"  to  "Cretaceous,"  made  for  the  sake  of  conformity 
with  Geological  Survey  usage.  In  his  recent  writings  Professor  Hyatt 
consistently  followed  the  International  Geological  Congress  rule  of  ending 
names  of  all  periods  and  systems  with  "ic." 

The  preparation  of  this  work  occupied  a  large  part  of  Professor 
Hyatt's  time  for  several  j'ears.  As  early  as  1897  a  manuscript  with  the 
same  title  was  submitted  to  the  Director  of  the  United  States  Geological 
Survey  for  publication,  and  soon  afterwards  the  preparation  of  the  illustra- 
tions was  begun.  A  copy  of  this  original  manuscript  now  in  my  hands 
shows  many  important  differences  in  aiTangement,  classification,  and 
nomenclature  from  the  later  manuscript,  indicating  that  it  had  been 
thoroughly  i-evised  and  recast  in  connection  with  a  restudy  of  the  fossils. 

Although  there  are  some  minor  inconsistencies,  and  there  would  doubt- 


11 


12  EDITOR'S  PREFACE. 

less  have  been  some  other  (-hanges  and  additions  if  the  author  liad  lived  to 
see  the  work  through  tlie  press,  it  is  believed  that  as  now  published  it 
fairly  presents  his  latest  views.     The  illustrations  were  all  made  under  Pro- 
fessor Hyatt's  supervision,  except  a  few,  which  were  definitely  selected  and 
indicated  by  him,  and  most  of  which  are  copies  of  published  figures.     He 
had  also  mounted  the  figures  on  the  first  twenty  plates  and  had  written  the 
descriptions  oi  nineteen  of  the  plates.     The  other  figures  were  nearly  all 
labeled  with  specific  names.     The  manuscript  was  in  two  packages,  one  of 
which  began  with  the  "General  remarks,"  followed  by  Pulchelliidse,  Knemi- 
ceratidfe,    Engonoceratida;,    and    Placenticeratidfe,    which    is    nearly    the 
arrangement  of  the  original  manuscript  of  1897,  while  the  second  package 
began  with  Mojsisovicsiida>  and  ended  with  Coilopoceratida'.     The  plates 
arranged  by  the  author  contain  all  the  illustrations  except  the  Placenticer- 
atidaj  and  a  part  of  the  Engonoceratidas.     By  transferring  the  introductory 
"General  remarks"  from  one  package  to  the  other  and  then  uniting  the 
two  packages  the  descriptions  fell  into  practically  the  same  arrangement 
that  was   adopted  for   the  figures,    and   which  evidently  represented  the 
author's  latest  views  as  to  their  relationships.     The  assignment  of  the  fami- 
lies to  higher  groups  was  not  fully  carried  out  by  Professor  Hyatt,  and  it 
is  thought  best  not  to  attempt  to  complete  it,  in  view  of  the  fact  that  his 
opinions  as  to  the  definition  and  limits  of  the  diff"erent  superfamilies  evi- 
dently were  much  modified,  though  never  formulated,  after  the  publication 
of  his  chapter  on  Cephalopoda  in  Zittel's  Text-l)ook  of  Paleontology.     In 
that  work  he  divides  the  Aramonoidea  into  several  suborders,  and  between 
these  and  the  families  there  is  another  unnamed  categor}-  of  groups,  which 
may    be    called    supei-families,    such    as    Mammitida,    Cosmoceratida,    etc. 
Part  of  the  Pseudoceratite  families  are  there  referred  to  Mammitida,  part 
to  Placenticeratida,  the  Pulchelliidse  were  accidentally  omitted,  and  f«ther 
families  were  not  there  described.     In  the  present  paper  a  list  of  the  fami- 
lies belonging  to  the  Mammitida  is  given,  but  beyond  that  group  the  clas- 
sification is  doubtful.     In  connection  with  the  description  of  Vascoceras, 
Cosmoceratida  is  mentioned  in  such  a  Avay  that  the  reference  of  the  genus 
to  that  group  may  be  inferred,  and  later  in  the  manuscript  the  heading 
:\Iautelliceratida  is  inserted,  but  there  is  nothing  to  wan-ant  the  assumption 


EDITOR'S  PREFACE.  13 

that  the  latter  term  was  mtended  to  include  HeinziidiT?,  PulcheUiida?,  Kneini- 
ceratidse,  Eugonoceratidse,  and  Placenticeratidji?.  In  the  jiuliHshed  work 
above  referred  to,  the  two  families  last  named  are  united  whh  Spheno- 
discida?  to  form  the  Placenticeratida,  but  with  the  removal  of  Sphenodis- 
cidffi  to  Mammitida  it  seems  probable  that  the  superfamily  Placenticeratida 
was  abandoned. 

The  multiplication  of  families,  g-enera,  and  species  will  be  understood 
by  all  who  are  acquainted  with  Professor  Hyatt's  habit  of  attempting  to 
express  in  the  terminology  every  important  fact  observed  in  the  course 
of  his  investigations. 

In  characteristic  fashion  the  author  plunges  into  the  midst  of  his 
subject,  beginning  his  introduction  with  a  discussion  of  the  sutural  details 
of  Jui-assic  ammonites,  not  tan-ying  even  to  define  the  title  of  the  paper  or 
to  make  a  formal  statement  of  the  problems  involved.  In  a  footnote  on 
page  546  of  Zittel's  Text-book,  where  he  first  used  the  term  Pseudocer- 
atites,  he  states  that  it  "is  a  descriptive  expression  for  the  Placenticeratida 
and  Tissotidfe  of  the  Cretaceous,  which  are  morphic  equivalents  of  some 
Triassic  genera  of  the  Discocampyli  as  regards  both  suture  and  shell  form. 
Their  origin  is  traceable,  however,  to  diff'erent  groups  of  the  Pachycampyli, 
a  suborder  which  appears  to  have  been  initiated  in  the  Jura  along  with  the 
Leptocampyli.  It  is,  therefore,  improbable  that  the  Pseudoceratites  were 
directly  connected  with  the  Triassic  Discocampyli."  In  a  letter  written 
December  26,  1901,  in  response  to  an  inquiry  from  the  Geological  Survey 
oflice,  he  gives  the  following  somewhat  more  definite  statement  of  the  scope 
and  purpose  of  the  present  work:  "I  am  at  work  finishing  a  'Monograph 
of  the  Pseudoceratites  of  the  Cretacic'  This  is  an  artificial  group,  includ- 
ing, for  convenience  of  treatment,  all  the  retrogressive  genera  of  the  Cre- 
tacic that  have  sutures  with  simple  outlines  resembling  those  of  Triassic 
cephalopods,  formerly  included  under  the  name  Ceratites.  The  known 
genera  described  and  figured  ai-e  Buchiceras,  Tissotia  and  its  allies,  Sphe- 
nodiscus,  Knemiceras,  Engonoceras,  Placenticeras.  The  aim  of  this  publi- 
cation is  to  give  as  full  treatment  as  possible  of  the  structure  and  relations 
of  these  genera,  in  order  to  determine  as  far  as  practicable  to  what  groups 
among  the  normal  progressive  forms  they  are  most  nearly  related." 


14  EDITOR'S  PREFACE. 

It  was  Professor  Hyatt's  custom,  in  citing  the  autliority  for  a  species, 
to  give  the  name  of  the  author  who  first  referred  the  species  to  the  genus 
in  which  it  is  now  retained,  instead  of  citing  the  one  who  first  proposed  the 
specific  name.  Thus  he  wrote  Placenticeras  placenta  Meek,  ahhough  the 
form  was  described  as  Ammonites  2)lacenta  by  DeKay.  This  is  not  in 
accordance  with  the  rule  usually  followed  by  zoologists,  and  the  citations 
have  been  changed  so  that  each  specific  name  is  followed  by  the  name  of 
the  original  describer  of  the  species,  with  the  author's  name  in  parentheses 
if  the  generic  reference  has  been  changed. 

When  the  figured  specimens  were  at  the  Geological  Survey  in  the 
hands  of  the  artists,  Professor  Hyatt  requested  the  writer  to  examine  them 
carefully  and  give  him  notes  and  comments  as  to  the  localities  and  horizons 
of  the  specimens  from  his  own  collection  and  from  other  museums.  The 
quoted  statements  concerning  various  species  that  appear  in  the  manuscript 
were  extracted  from  the  notes  the  writer  then  forwarded  to  him. 

The  appended  tabular  statement  is  intended  to  show  the  relative 
positions  of  the  various  marine  Cretaceous  horizons  and  formations  men- 
tioned in  the  text.  It  does  not  imply  accurate  correlation  of  American  and 
European  horizons,  the  line  between  Lower  and  Upper  Cretaceous  being 
probably  somewhat  higher  in  America  than  in  Europe. 

The  figured  specimens  that  are  mentioned  in  this  paper  as  belonging 
to  Professor  Hyatt's  private  collection  have  now  become  the  property  of 
the  Museum  of  Comparative  Zoology  in  Cambridge. 

The  writer  has  supplied  the  table  of  contents,  tlie  formal  bibliographic 
list,  and  the  descriptions  of  the  plates  after  PI.  XIX. 

T.  W.  Stanton. 


CLASSIFIED  LIST  OF  FAMILIES.  GENERA,  AND  SPECIES. 

In  the  following  list  all  the  groujis  that  are  described  an<l  all  the 
species  that  are  definitely  referred  to  the  genera  herein  treated  are  arranged 
according  to  Professor  Hyatt's  classification  as  given  in  the  text.  The 
purpose  of  the  list  is  to  bring  together  in  compact  form  for  eas}^  reference 
the  large  number  of  described  species  that  are  here  referred  to  new  genera. 

The  classification  is  incomplete  and  in  some  cases  probably  misleading. 
For  example,  some  of  the  genera  under  Cosmoceratida  are  not  assigned  to 
families,  and  it  is  very  doubtful  whether  Professor  Hyatt  intended  to  place 
in  Mantelliceratida  all  the  families  here  arranged  under  that  superfamily. 
It  is  evident  that  the  author's  published  views  concerning  that  grouj)  had 
changed,  but  unfortunately  he  had  written  no  revised  description.  It  is 
therefore  necessary  to  leave  the  groups  classified  according  to  the  arrange- 
ment of  the  manuscript  without  inserting  the  names  of  any  other  super- 
families. 

T.  W.  S. 


MAMiMITIDA. 

MOJSISOVICSIID^. 


Mojsisovicsia  Steinmann. 
dnrfeldi. 


BUCHICERATID^. 


Bucliiceras  Hyatt. 

liiloljatuni. 
Roemeriiceras  Hyatt. 

gal)bi. 

syriaciforme. 

attenuatum. 

f^ubplanum. 


PSEUDOTISSOTIID^. 


Pseudotissotia  Perun. 
galliennei. 
tunisiensis. 


Choffatiteras  Hyatt. 

barjonai. 

meslei. 

douvillei. 
Hemitissotia  Peron. 

cazini. 

batnensis. 

morreni. 

tissotiieformis. 

djelfensis. 

ceadouroensis. 
Plesiotissotia  Peron. 

michaleti. 


TlSSOTIID^. 


TisBOtia  Douvill^. 

tissoti. 
Subtipsotia  Hyatt. 

iiifiata. 

intermedia. 

peroni. 

africana. 


15 


16 


PSEUDOCEKATITES  OF  THE  CRETACEOUS. 


Metatissotia  Hyatt. 

foin-neli. 

robini. 

nodosa. 

haplophylla. 

ewaldi. 

auressensis. 

slizewiczi. 
Paratissotia  Hyatt. 

grossouvrei. 

thomasi. 

ficheuri. 

serrata. 

regularis. 


Incert^  sedis. 

Tissotia  cossoni. 

globosa. 
Heterotissotia  Peron. 

neoceratites. 

Sphenodiscid^. 

Indoceras  Noetling. 

baluchistanense. 

actitodorsatum. 
Libycoceras  Hyatt. 

ismaele. 
Sphenodiscus  Meek. 

pleuriaepta. 

lobatus. 

stantoni. 

lenticularis. 

var.  splendent, 
var.  mississippiensis. 

beecheri. 

konincki. 

biiu'khorsti. 

ubagshi. 

nitoti. 

siva. 

EULOPHOCERATID^. 

Tegoceras  Hyatt. 

mosense. 
Leiitioeras  Gerhardt. 

andii. 
Paralenticeras  Hyatt. 

siever-si. 
Euloijhoceras  Hyatt. 

natalense. 

COILOPOCERATID^. 

Platylenticeras  Hyatt, 
heteropleurum. 


pseudograsianum. 
gevriliauuin. 


Coilopoceras  Hyatt. 

colleti. 

novimexicanum. 

springeri. 

requienianum. 

grossouvrei. 
AcoiieceraH  Hyatt. 

nisum. 

COSMOCERATIDA. 

Vascoceras  Cbiiffat. 

hartti. 
Tolypeceras  Hyatt. 

marcotisanuiu. 
Barroisiceras  Grossouvre. 

desmoulinsi. 

haueri. 

MANTELLICERATIDA. 

MANTELLICERATlD.a;. 

Metasigaloceras  Hyatt. 

rusticuin. 
Pseudaspidoceras  Hyatt, 
footeanum. 
eoiiciliatuin. 
cunliffi. 
crassitesta. 
euomphalum. 
deciduum. 
schliiteri. 
Diadochoceras  Hyatt, 
nodosocostatuin. 
Pedioceras  Gerhardt. 
curnlinamarcae. 
caquesensis. 
ubaquensis. 
Douvilleiceras  Gi-ossouvre. 
maniinillare. 
orl)ignyi. 
spinitVruiii. 
Schluetericeras  Hyatt, 
nodosoides. 
vielband. 
lauliei. 

niichelobense. 
Sharpeioeras  Hyatt, 
laticlaviuin. 
Sfhlut'tcri. 
inconstans. 
Aconipsoceras  Hyatt, 
bochumeiise. 
essendense. 
renevieri 


CLASSIFIED  LIST  OF  FAMILIES.  GENERA,  AND  SPECIES.  17 


Mantelliceias  Hyatt, 
niantelli. 
couloni. 
picteti. 
vicinale. 
ushas. 
indianense. 
domevkanum. 


Metoicoceratid^. 


Metoicoceras  Hyatt, 
swallovi. 
gibbosum. 
whitei. 
acceleratum. 


Heinziid^. 


Heinzia  Sayn. 

sayni. 

corioli. 

heinzi. 

hispanica. 

pulchelliformis. 

provincialis. 

matura. 

ouachensis. 
Carstenia  Hyatt. 

lindigi. 

caicedi. 

subcaicedi. 

tubereulata. 

galeata. 
Gerhardtia  Hyatt. 

galeatoides. 

galeatus. 

veleziensis. 


PuLCHELLIID^aE. 


Nicklesia  Hyatt. 

moltoi. 

levyi. 

nolaiii. 

lapparenti. 

alicantensis. 

karsteni. 

lenticulata. 

didayana. 

dumasiana. 
Subpulchellia  Hyatt. 

oehlerti. 

fouquei. 

sauvageaui. 

castellanensis. 


Pulchellia  Uhlig. 

nicklesi. 

schluiubergeri. 

Columbiana. 

selecta. 

hettneri. 

fliangarnieri. 

kiliani. 

ouachensis. 

compressissima. 
Psilotissotia  Hyatt. 

chahnasi. 

niariola>. 

defforgesi. 

reigi. 

haugi. 
Lopholiolite.s  Hyatt. 

eotteaui. 

Knemiceratid^. 

Knemiceras  Bohni. 
syriacum. 
coinpressuin. 

var.  subcompressum. 
attenuatum. 
gabbi. 
uhligi. 

ENGONOCERATID.aE. 


Protengonoceras  Hyatt, 
gabbi. 
planum. 

eniarginatmn. 
Engonoeera.s  Neuuiayr. 

belviderense. 

uddeni. 

serpentinum. 

pierdenale. 

var.  commune. 

subjeetum. 

gibbosum. 

stolleyi'. 

complicatuni. 

emarginatum. 

roemeri. 
Neolobites  Fischer. 

vibrayeanus. 

choffati. 

ptToni. 
Metengonoceras  Hyatt. 

inscriptum. 

ambiguum. 

acutum. 

dumbli. 


MON   XLIV — 03 2 


18 


PSEUDOCEKATITES  OF  THE  CRETACEOUS. 


Placenticeratid^. 


Placenticeras  Aleek. 
guadalupa". 
sancarlosense. 

var.  pseudosyrtale. 
planum, 
newberryi. 
syrtale. 

var.  halei. 
intercalare. 
placenta, 
stantoni. 

var.  boUi. 
pseudoplacenta. 

var.  occidentale. 
whitfieldi. 

var.  tuberculatum, 
spillmani. 
telifer. 
?  fallax. 
ebravi. 


Placenticeras  warthi. 

nieinoria-schloenbachi. 

(lepressum. 

grossouvrei. 

incisum. 

niilleri. 

scliliiteri. 

orbignyanum. 

polyopsis. 

erassatum. 

taniulicuni. 

pseudcirbignyanum. 

subtili^Jtriatunl. 
Diplacmoceras  Hyatt. 

Ijidorsatum. 

canaliculatum. 

Incert.*;  sedis. 


Styracoceras  Hyatt, 
balduri. 

Tahle  of  horizons  mentioned  in  this  work. 


Upper  Missouri. 

Texas. 

Gulf  border. 

New  Jersey. 

Europe. 

Fox  Hills. 

Navarro,  Eagle  Pass. 

Ripley. 

Manasquan 

Danian. 

MontHiia 

(Upper 
marl). 

Fort  Pierre. 

Taylor,  San  Carlos. 

Selma(  Rot- 

Rancocas 

i 

ten  lime- 

(Middle 

stone)  . 

marl). 

rCampanian. 

3 

Monmouth 

SenoniamSantonian. 

(Lower 

Iconiacian. 

u 

a; 
P. 

ft 

Niobrara. 

Austin. 

Eiitaw. 

marl) . 
M  a  t  a  w  a  n 

Colorado 

Fort    Ben- 
l    ton. 

Eagle  Ford. 

(Claymarl). 

Turonian. 

Dakota. 

Woodbine. 

Cenomanian. 

Buda. 

Grayson. 

Main  street. 

Albian.  Gault 

llellisoii 

Paw  Paw. 

X 

Washita 

Marietta. 

§ 

_a3 

Denton. 

1 

0) 

o 
g 

Fort  Worth. 

IDuck  Creek. 
Preston      .      .  . 
[Kiamitia. 

Aptian. 

1 

a 

(Edwards. 

3 

6 

Frederick.«burg|ciimanehe  Peak. 

[Walnut. 

jPaluxy. 
Trinity joienrose. 

[Travis  Peak. 

Barremian. 

Hauterivian. 
Neoeomian   ,.  , 

V  rtlangian. 

Berriassian. 

PSEUDOCERATITES  OF  THE  CRETACEOUS. 


By  Alpheus  Hyatt. 


GENERAL  REMARKS. 

So  far  as  I  have,  been  able  to  see,  either  in  figm-es  or  in  specimens,  the 
Amnionitinje  of  the  Jura  have  only  one  large  tirst  lateral  lobe,  even  in  highly 
involute  forms,  as  demonstrated  by  the  admirable  researches  of  Buckman" 
upon  HyperUoceras  discoidum,  suhdiscoidum,  etc.,  and  the  same  has  been 
shown  by  Oppel's  figures*  of  Neumayria  discus,  hochstetteri,  and  aspidoides, 
and  Quenstedt  mAmm.  trueUi,'and  the  similar  hollow-keeled  forms  alsoiniVeif- 
mayria  serrodens  (pis.  24,  69),  Polyplectus  diseoides,  and  capeUinus  (pi.  53), 
which  have  a  very  deeply  divided  and  double  first  lateral,  and  in  Neumayria 
discus  (pi.  57)  in  which  there  are  apparently  two  or  three  principal  laterals,  but 
in  the  neanic  stage  only  one  bifid  first  lateral  The  Arietidse  seem  to  have 
two  principal  saddles  owing  to  the  great  development  of  first  auxiliary,  but 
this  occurs  only  in  the  ephebic  stage.  Aspidoceras  and  some  forms  of  other 
genera  often  have  two  well-divided  principal  lateral  saddles,  but  this  again 
occurs  through  the  late  division  of  the  primitive  lateral. 

In  fact,  it  may  be  confidently  stated  that  in  the  Jura  all  of  the  Ammo- 
nitinse  have  but  one  principal  lateral  saddle  throughout  the  neanic  stage, 
and  when,  as  very  rarely  occurs,  two  or  three  principal  laterals  are  either 
apparently  or  actually  developed,  they  occur  as  pui-ely  secondary,  or  rather, 
tertiary  developmental  changes  in  the  ephebic  stage. 

This  fact  is  of  importance  because  of  its  bearing  u})on  the  biology  of 
Ammonitinte  in  the  Cretaceous.  With  regard  to  these,  it  may  be  stated 
that  they  are  distinctly  tachygenetic  or  accelerated  in  development  when 

"Inferior  Oolite  Ammonites:  Palseont.  Soc,  Vol.  II,  pp.  40-49. 

*Pal.  Mittheil.,  pi.  4. 

^■Amm.  (1.  schwiib.  Jura,  pis.  24,  69. 

19 


20         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

compared  with  the  Ammonithise  of  the  Jura.  All  of  the  forms  so  far  inves- 
tigated, which  have  more  than  one  principal  lateral  saddle  and  lobe,  acquire 
these  characters  a  stage  earlier  than  the  Jurassic  species.  They  appear,  as 
stated  above,  in  the  neanic  stage  and  are  secondary  modifications  of  the 
outlines  of  the  primitive  first  laterals  of  the  nepionic  stage. 

The  same  law  seems  to  hold  in  a  modified  way  for  the  development  of 
an  extra  unmber  of  auxiliary  lobes  and  saddles  such  as  appear  in  Ncumayria, 
but  my  materials  have  not  enabled  me  as  yet  to  follow  this  out.  This 
statement  appears  at  first  sight  to  be  antagonized  by  that  made  with 
reference  to  the  arrested  development  of  the  sutures  in  genera  like 
Protengonoceras,  Engonoceras,  etc.,  which  have  undivided  or  bifid  saddles 
and  lobes  only  slightly  digitated  at  their  extremities.  But  it  will  be  shown 
in  the  generic  description  of  Placcnticeras  that  the  arrest  of  development 
takes  eff"ect  in  these  Pseudoceratites  of  the  Cretaceous  only  after  the 
three  principal  lateral  saddles  and  lobes  are  formed  in  the  neanic  stage. 
Consequently,  up  to  this  stage,  the  development  is  more  complex  than  in 
the  young  of  Jurassic  species  or  any  others  which  have  only  one  principal 
lateral  at  the  same  age.  This  statement  clears  up  the  extraordinary  relations 
of  these  forms  to  their  apparently  more  complicated  allies  of  the  Jurassic, 
and  accounts  also  for  the  apparent  discrepancy  existing  between  the  highly 
involute  compressed  character  of  the  whorls  during  the  neanic  stage  and 
the  very  simple  aspect  of  the  lobes  and  saddles;  that  such  highly  involute 
compressed  forms  in  the  Jura,  usually  combined  with  the  development  of 
highly  complex  lobes  and  saddles,  has  been  recorded  by  me  in  other  papers 
and  Ijy  many  other  writers;  consequently,  when  one  meets  the  Pseudocera- 
tites  of  the  Cretaceous  he  is  apt  to  imagine  them  to  be  what  Barrande  has 
called  "anaclu-onisms,"  and  difficult  problems  for  the  evolutionist.  They 
are  unquestionably  difficult,  but  they  are  no  more  anachronic  than  any  of 
the  forms  usually  named  as  having  this  paradoxical  character.  They  are 
simply  excellent  examples  of  arrestation  of  development  taking  efi"ect 
locally  and  upon  certain  structures.  These,  if  1  have  rightly  understood 
the  researches  of  my  deceased  friend.  Professor  Cope,  the  most  brilliant 
investigator  and  profoundest  thinker  on  evolution  that  America  has  pro- 
duced, are  good  examples  of  his  law  of  retardation  in  development,  and 
also  excellent  examples  of  the  difterent  way  in  which  I  look  upon  the  same 
phenomena.     I  have  never  regarded  such  cases  as  examples  of  a  tendency 


GENERAL  REMARKS.  21 

to  retardation  of  development.  A  distinction  exists  between  arrestation 
and  retardation  in  development,  winch  is  of  great  importance.  Arrest  of 
development  occurs  in  many  ways.  It  may  take  effect  locally,  as  upon  the 
sutures,  stopping-  them  from  developing  in  complexity  of  outline  beyond  a 
certain  measure,  and  thus  retaining  a  semblance  to  their  own  young  and 
apparently  reverting  to  the  condition  of  the  same  parts  in  more  ancient 
animals  of  their  own  stock.  It  may  take  effect  upon  the  whole  organism, 
as  in  BacuUtes  and  other  uncoiled  forms,  apparently  causing  the  entire 
animal  to  revert  in  its  characters  to  a  primitive  form.  There  are  imuimer- 
able  degrees  between  these  two  extremes  which  it  is  not  necessary  nor 
appropriate  to  mention  here.  Retardation  is  distinct  from  these  and  of 
much  rarer  occurrence. " 

The  development  can  not  be  said  to  have  been  retarded  in  these 
retrogressive  forms,  since  it  begins  and  for  a  certain  period  in  the  ontogeny 
progresses  in  jiarallel  lines  with  the  ancestors  of  the  group,  but  passes 
through  the  modifications  more  quickly  according  to  the  law  of  tacliy- 
genesis.  After  this  its  progress  is  quite  suddenly  and  decidedly  arrested, 
and  the  succeeding  stages  are  no  longer  parallel  with  those  of  their 
ancestral  forms.  The  complexity  of  the  outlines  of  the  lobes  and  saddles 
in  species  of  Engonoceras,  for  example,  does  increase  even  in  the  later 
stages;  but  this  increase  is  very  slight,  and  the  result  is  a  retrogressive 
form  that  mimics  to  a  certain  extent  jwimitive  forms  among  Goniatitinse 
and  Ceratitinse.  Such  examples  may,  nevertheless,  belong  to  the  highly 
accelerated  class,  as  is  shown  by  the  earlier  development  in  these  Pseudo- 
ceratites  of  the  Cretaceous  of  the  three  principal  saddles  that  only  appear 
in  the  ephebic  stage  of  the  highly  progressive  forms  among  Annnonitinaj 
of  the  Jura.  Retardation  of  development  certainly  does  not  take  place 
in  their  early  stages.  Can  it  be  said  to  take  place  because  they  do  not 
subsequently  jjroceed  to  develop  numerous  marginal  lobes  and  saddles  on 
the  borders  of  these  same  lobes  and  saddles'? 

Retardation  of  development  can  mean  but  one  class  of  phenomena,  viz, 
those  cases  in  which  a  character  appears  in  the  ontogeny  of  descendants 
later  than  the  stage  at  which  it  appeared  in  the  life  of  their  ancestors.  In 
cases  of  retrogression  such  as  are  noted  above,  and  in  all  examples  of  this 
class  with  which    I    am  acquainted,   the  complication  of  the  lobes  and 

« Bioplastology  and  related  branches  of  biologic  research;  Proc.  Boston  Soc.  Nat.  Hist.,  Vol. 
XXVI,  p.  79,  etc. 


22         PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

saddles  by  the  addition  of  marginals  during  the  later  stages  of  the  ontog- 
eny does  not  occur;  the  inexact  parallelism  is  produced  by  the  dropi)ing 
out  of  this  stage  completely,  not  by  its  later  and  later  development. 
Cope,  in  his  great  work  Origin  of  the  Fittest,  writes  as  follows:" 

*  *  *  The  acceleration  in  the  assumption  of  a  character,  progressing  moro  rap- 
idly than  the  same  in  another  character,  must  soon  produce,  in  a  type  whose  stages  were 
once  the  exact  parallel  of  a  permanent  lower  form,  the  condition  of  inexact  parallelism. 
As  all  the  more  comprehensive  groups  present  this  relation  to  each  other,  we  are  com- 
pelled to  believe  that  acceleration  has  been  the  principle  of  their  successive  evolution 
durino-  the  long  ages  of  geologic  time. 

Each  type  has,  however,  its  da^-  of  supremacy  and  perfection  of  organism,  and 
a  retrogression  in  these  respects  has  succeeded.  This  has,  no  doubt,  followed  a  law 
the  reverse  of  acceleration,  which  has  been  called  retardation.  By  the  increasing 
slowness  of  the  growth  of  the  individuals  of  a  genus,  and  later  and  later  assumption 
of  the  characters  of  the  latter,  they  would  be  successively  lost. 

To  what  power  shall  we  ascribe  this  acceleration.  l>y  which  the  first  begin- 
nings of  structure  have  accumulated  to  themselves  through  the  long  geologic  ages 
complication  and  power,  till,  from  the  germ  that  was  scarcelj'  born  into  a  sand 
lance,  a  human  being  climbed  the  complete  scale  and  stood  easily  the  chief  of  the 
whole?     *     *     * 

Acceleration  signifies  addition  to  the  number  of  those  repetitions  during  the 
period  preceding  maturity  as  compared  with  the  preceding  generation,  and  retarda- 
tion signifies  a  reduction  of  the  numbers  of  such  repetitions  during  the  same  time.* 

Thus,  from  Cope's  point  of  view,  tachygenesis  is  the  law  of  progression, 
and  retardation  is  the  law  of  retrogression,  and  they  are  both  essential  parts 
of  his  law  of  acceleration  and  retardation. 

These  qi;otations  show  that  we  both  have  the  same  conception  of 
the  proper  use  of  the  word  "retardation,"  but  we  differ  in  the  application 
of  it.  He  applied  it  to  such  cases  as  are  described  here  among  Pseudo- 
ceratites,  whereas  I  regard  these  as  true  arrests  of  development  and  not  as 
retardations. 

Retardation  is  exceedingly  rare  among  Anmionitinse,  and  as  a  rule  in 
other  parts  of  the  animal  kingdom,  and  the  only  examples  I  am  able  to  cite 
are  like  those  given  below  in  Placentkeras,  where  the  more  complex  species 
like  ivhifJiehU,  that  are  obviously  descended  from  species  like  P.  syrtale, 
liave  apparently  the  nodes  and  ornaments  smaller  and  developing,  as  a  rule, 
]at(-r  than  in  that  species,  and  iinall}',  in  extreme  forms  like  those  of  typical 
ivhltfieldi,  disappearing  altogether. 

«P.  142.  ''P.  182. 


GENERAL  REMARKS.  23 

As  a  rule,  among  Ammonitinae  the  reverse  is  the  case,  and  the  disap- 
pearance of  characters  takes  place  through  the  earliei'  and  earlier  develoj)- 
ment  and  shorter  and  shorter  life  history  of  each  characteristic,  or  through 
tachygenesis,  as  stated  and  illustrated  in  many  of  my  papers.  Here  I  have 
space  only  for  one  quotation,  which  will  serve  to  show  my  meaning  more 
plainly : 

Specialization  by  reduction  of  parts  is  evidently  included  under  the  head  of 
retardation  by  Cope;  thus  in  Oi"igin  of  the  Fittest  (p.  353),  he  says  that  ''change  of 
structure  during  growth  is  accomplished  either  by  addition  of  parts  (acceleration)  or 
by  subtraction  of  parts  (retardation)."  So  far  as  my  experience  goes,  in  the  major 
number  of  cases  the  parts  or  characters  that  are  undergoing  reduction  disappear 
according  to  the  law  of  tachygenesis.  They  reappear  in  the  ontogeny  at  earlier 
and  earlier  stages,  or  exhibit  this  tendency  in  the  same  way  as  characters  of  the 
progressive  cla.ss,  but  their  development  is  not  so  complete  as  in  ancestral  forms.  In 
this  sense  they  can  be  regarded  as  retarded  or  thrown  back  in  their  development. 
There  is,  however,  another  way  of  formulating  the  expre.ssion  of  this.  Instead  of 
regarding  this  disappearance  by  retrogressive  gradations  as  due  to  a  tendency 
opposed  to  acceleration,  is  it  not  a  tendency-  of  the  same  kind?  That  is  to  say,  do 
not  the  parts  and  characters  show  a  tendency  to  disappear  earlier  and  earlier,  and  are 
the}'  not  in  most  cases  at  the  time  of  disappearance  present  only  in  earlier  stages  of 
growth  than  that  in  which  they  originated  in  ancestral  forms? 

Is  not  the  case  of  the  wisdom  teeth  exceptional?  The  frequently  extremely  late 
external  appearance  of  the.se  is  not  accompanied  })y  a  later  origin  of  their  rudiments 
in  the  jaw.  Although  they  may  not  appear  in  many  cases  above  the  gum  until  a 
person  is  past  iif  ty,  is  not  this  real  retardation  due  primarily  to  the  fact  that  they  are 
deficient  in  growth  power  (tending  to  disappear  from  disuse,  etc.),  and  secondarily  to 
their  internal  position?  When  they  cease  to  be  able  to  break  through  the  gum  will 
they  not  still  continue  to  develop  at  the  same  stage  as  the  other  teeth,  and  will  not 
their  rudiments  be  likely  to  be  present  at  this  early  stage  long  after  they  have  ceased 
developing  into  perfect  teeth  ?<* 

The  whalebone  whales  are  examples  of  this  kind  so  far  as  the  teeth  are 
concerned,  although  here  the  disappearance  is  correlated  with  the  develop- 
ment of  whalebone  from  the  rugae  of  the  roof  of  the  mouth.  Nevertheless 
the  suppression  of  the  teeth  in  full-grown  animals  does  not  take  place  bj' 
later  and  later  development,  and  the  rudiments  of  the  teeth  are  still  present 
in  the  early  stages. 

"Biopla-stology;  Proc.  Boston  See.  Nat.  Hist.,  Vol.  XXVI,  note  to  p.  80. 


SYSTEMATIC   DESCRIPTIONS. 

This  group  in  my  chapter  on  Cephalopoda  in  Zittel's  Text-book  con- 
tained a  number  of  keeled  families,  in  which  either  the  keel  was  preceded 
by  a  median  line  of  tubercules,  or,  if  this  stage  were  omitted,  the  smooth 
keel  arose  upon  the  venter  in  forms  that  were  apparently  closely  allied  to 
the  more  primitive  genera  having  these  tuberculated  keels.  The  Mam- 
mitida  included  Mammitidte,  Peronicei-atidse,  Prionotropidpe,  Hystato- 
ceratida?,  Lenticeratidne,  and  Tissotiidse.  To  these  I  propose  to  add  now 
the  Mojsisovicsiida?,  Buchiceratidse,  Pseudotissotiidse,  Eulophoceratidse,  Sphe- 
nodiscidte,  and  Coilopoceratidse. 

MOJSISOVICSIIDiE    Hyatt. 

The  single  genus  and  species  described  below  can  not  be  even  pro- 
visionally included  in  any  of  the  gi'oups  to  which  it  is  supposed  to  be 
nearly  related,  and  the  following  discussion  of  its  generic  affinities  shows  this 
conclusively.  The  dorsal  futures  are  not  yet  known,  and  this  is  the  only 
defect  in  the  evidence  that  establishes  it  as  an  independent  group,  probably 
belonging  to  the  parent  stock  or  stem  of  the  Pachycampyli. 

MOJSISOVICSIA  Steinmann. 

The  interesting  species  used  as  the  type  of  this  genus  has  a  form 
which  is  similar  to  that  of  Agassiceras  of  the  Lower  Lias  in  being  smooth 
and  discoidal,  with  flattened  sides,  narrow  umbilical  zones  and  rounded 
venter.  The  section  is  what  I  have  called  helmet  shaped,  like  Acjas.  striar- 
ies.  It  differs  in  having  no  raised  line  or  keel,  and  therefore  comes  a  little 
nearer  to  Psiloceras.  The  sutures  bear  a  similar  interpretation,  since, 
although  these  are  very  immature,  there  are  four  lateral  bitid  saddles  with 

"A  penciled  note  at  the  top  of  this  page  of  manuscript  says  "Revise  list."  Just  what  changes 
the  author  would  have  made  can  not  be  known,  but  it  may  V)e  inferred  that  Lenticeratiihe  was 
dropped  as  an  aV)andoned  family,  and  that  possibly  C'(>ilo[)oceratidie  was  assigned  to  another  super- 
family.  It  is  obvious  that  his  conception  of  the  group  Mammitida  had  become  very  different  from 
that  expressed  by  him  in  Zittel's  Text-book. — T.  W.  S. 
24 


MOJSISOVICSIID^.  25 

siibpliylliform  marginal  saddles  and  excessively  short  pointed  marg-inal 
lobes  that  are  hardly  more  than  serrations.  The  ventral  lobe  is  very  broad 
and  divided.  The  tirst  and  second  lateral  lobes  are  narrow  and  similar  to 
tliose  of  BucMceras,  bnt  it  should  be  noted  that  the  dorsal  sutures  are 
unknown,  and  these  may  l)e  quite  distinct.  The  third  lateral  lobe  is  entire, 
and  the  fourth  saddle  hardly  past  the  entire  stage,  exhibiting  only  a  slightly 
triiid  outline.  Such  sutures  exhibit  affinities  with  the  smooth  primitive 
ancestral  stock  of  the  Psiloceratidfe  of  the  Jura  and  other  forms  of  Pachy- 
campyli  descended  from  these  because  of  their  massive  broad  saddles,  so 
entirely  different  from  the  narrow,  excessively  branched  saddles  of  the 
Phyllocampyli  ami  Leptocampyli.  I  do  not,  of  course,  mean  that  Mojsiso- 
vicsiu  is  probably  descended  directl}^  from  Psiloceras,  l)ut  it  may  be  a  Cre- 
taceous member  of  a  primitive  stock  which  began  with  Psiloceras  in  the 
Jura.  The  intermediate  forms  are  as  yet  unknown  or  have  not  been  pul)- 
lished.  The  existence  of  such  a  trunk  or  main  branch  of  a  primitive  stock 
from  which  all  of  the  more  complex  groups  are  lateral  offshoots  has  been 
inferred  from  the  ontogeny  as  the  most  probable  way  to  account  for  the 
ontogeny  of  the  primitive  species  of  these  groups.  Thus  in  the  present 
instance  the  smooth  discoidal  young  of  Buclikeras  and  other  genera  can  be 
readily  accounted  for  if  the  comparison  between  tliem  and  the  later  stages 
of  Mojsisovicsia  is  admitted.  If  such  a  stock  of  primitive  forms  existed,  it 
is  also  easy  to  account  for  the  maintenance  of  such  primitive  smooth  psilo- 
ceran-like  shells  in  the  later  nepionic  and  sometimes  in  the  neanic  stages  of 
Cretaceous  fonns  Otherwise  the  continued  renewal  of  these  in  the  ontos"- 
eny  at  such  late  stages  must  be  referred  to  more  ancient  ancestors  than  any 
rej)resented  in  the  Jura. 

Mojsisovicsia  durfeldi  Steinmann. 

PI.  I,  figs.  1-3. 

Jfojs/'sovicsia  durfvldl  Stcinmiuin,  Neues  Jahrbuch  fiir  ]Min.,  Geol.,  unci  Pal.,  1881, 
11,  p.  143,  pi.  6. 

The  pecuhar  fossil  described  under  this  name  has  a  compressed  discoidal 
shell  with  slight  constrictions,  open  umbilici,  and  smooth  surface  that  in 
external  aspect  resembles  Traneceras  and  also  some  of  the  discoidal  Desmo- 
ceratidff  like  Pseudophyllites  Kossmat,  but  has  entirely  different  sutures. 
These  liave  an  asj^ect  similar  to  those  of  Buchiceras  hilohatuiii,  but  the  form 
of  the  AM)lution  differs  so  widely  that  no  further  comparisons  can  be  itiade 


26         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

with  this  genus.  The  living  oluimber  is  short,  the  aperture  lias  a  l)huit 
rostrum,  there  are  shallow  sinuses  on  the  edges  of  the  venter,  a  Inroad 
lateral  rostrum  on  either  side,  and  shallow  sinuses  between  these  and  the 
umbilical  shoulders,  and  probably  a  crest  on  the  dorsum. 

The  ventral  lobe  is  very  broad  and  short,  with  a  broad  short  siphonal 
saddle.  There  are  three  bifid  lateral  saddles,  with  an  incomplete  apparently 
entire  saddle  at  the  line  of  involution.  The  lobes  are  short  and  much 
narrower  than  the  saddles,  and  the  entire  outlines  of  both  lobes  and  saddles 
have  short  obtuse  marginal  saddles  and  narrow,  short,  pointed,  simple 
marginal  lobes. 

The  species  is  known  to  me  only  through  Steinmann's  figures,  wliich 
are  reproduced  on  PI.  I,  figs.  1-3,  with  the  single  exception  of  his  enlarged 
drawing  of  the  side  view  of  fig.  1. 

Locality:  Pariatambo,  Peru. 

Age:  Albian  (?). 

BUCHICERATID^    Hyatt. 

It  has  been  found  impracticable  to  unite  the  genus  Buchkeras  with  any 
known  family,  on  account  of  its  peculiar  development  and  sutures.  The 
approximation  to  the  rlystatoceratidse.  is  close,  so  far  as  the  earlier  stages 
are  concerned,  the  compressed,  comparatively  smooth-keeled  young  in  the 
neanic  stage  having  considerable  resemblance,  but  these  similarities  are  lost 
in  the  subsequent  developmeiit,  owing  to  the  partial  suppression  of  the  costse 
and  the  very  distinct  sutures.  The  development  and  sutures  separate  these 
forms  completely  from  Kncmiceras.  They  are  separable  from  Tissotiida?  by 
their  first  lateral  saddles  and  their  ventral  lobes,  and  from  Barroisiceras, 
which  they  also  resemble,  by  the  absence  at  all  stages  of  a  third  line  of 
tubercles  and  by  their  sutures. 

The  sutures  are  similar  to  those  of  the  discoidal  smooth  shell  of  uncer- 
tain affinities  described  as  Mojsisovicsia  by  Steinmann. 

So  far  as  known  there  are  no  representatives  of  this  genus  except  in 
South  America.  It  slioidd  be  remembered,  however,  that  all  information 
heretofore  published  has  cimie  from  this  single  fossil. 

The  second  genus  included  in  this  family,  Roemeroceras,  has  similar 
ventral  lobes  and  siphonal  saddles,  and  the  young,  although  (juite  distinct 
in  l)eing  less  compressed  in  the  early  stages,  acquire  a  similar  keel  at  a 
later  age,  and  similar  form  and  ornaments. 


BLTCHICERAT1D.E.  27 

BUCHICERAS   Hyatt. 

This  genus  was  formerly  described  V)y  mj^self  as  including-  several 
different  species  that  have  since  been  separated  into  distinct  genera,  by 
Douvilld,  Grossouvre,  and  others,  and  by  myself,  iu  Zittel's  Text-book  of 
Paleontology.  The  affinities  of  Buchiceras  are  not,  in  ray  opinion,  very 
close  to  any  of  the  forms  formerly  referred  to  Acanthoceras  as  supposed  by 
some  authorities.  The  sutures  are  quite  distinct  from  those  of  any  of  the 
families  of  Mannnitida  on  account  of  the  extraordinary  breadth  of  the  second 
lateral  saddles.  The  development  is  similar  to  that  of  some  forms  of  Hys- 
tatoceratidfe  and  Peroniceratida?  in  that  it  is  at  first  discoidal,  compressed, 
and  smooth,  then  keeled,  becoming  costated  and  tuberculated  later,  and 
the  sutures  approximate  more  closely  to  those  of  the  young  of  these  families 
perhaps  than  to  others.  Nevertheless  the  ontogeny  differs  in  that  Buch- 
ireras  does  not  subsequently  acc^uire  prominent  costa?,  and  the  keel  tends  to 
disappear  instead  of  becoming  larger  with  increase  in  size  of  the  volutions. 
The  nodes,  on  the  other  hand,  increase  in  size  and  prominence,  especially  the 
inner  row  on  the  umbilical  shoulders.  The  faint  sen-ations  on  the  keel  and 
other  ornamentation  suggest  affinities  with  Barroi  steer  as,  but  the  sutures  and 
the  absence  of  a  third  line  of  lateral  tubercles,  which  appear  in  some  forms 
of  Barroisiceras,  are  not  favorable  to  this  solution  of  the  affinities.  The 
same  objections  apply  almost  equally  to  keeled  forms  of  the  Prionotropidae 
in  which  the  young  resemble  more  or  less  closely  those  of  B.  Ulohatum. 
The  dorsal  sutures  are  very  remarkable  and  perhaps  may  eventually  assist 
in  placing  this  genus  in  closer  connection  with  others.  The  primitive  first 
lateral  saddle  is  retained  in  Buchiceras  until  a  late  stage,  and  perhaps 
throughout  life ;  it  is  undivided,  except  by  small  entire  marginal  lobes,  but 
it  is  distinctly  bifid. 

Buchiceras  hilobatum  Hyatt. 
PI.  I,  figs.  4-y. 

Buc/t/'ce^w  hllulatum  Hyatt,  1875,  Proc.  Boston  Soc.  Nat.  Hist.,  Vol.  XVH,  p.  .37u. 
Buchiceras  hllobatum  Douville,  1890,  Bull.  Soc.  geol.  France,  3d  ser.,  Vol.  XVIII, 
p.  284. 

The  young,  for  the  first  two,  and  perhaps  part  of  the  third  volution, 
must  have  had  smooth  sides  and  was  obviously  very  discoidal,  flat,  and 
keelless.  The  aspect  of  this  species  must  have  been  very  similar  to  Mojsi- 
sovicsia.     The  keel  comes  in  upon  an  elevated  venter  previous  to  reaching 


28         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

the  diameter  of  5  inin.  and  is  faintly  sinnous  during  tlie  latter  part  of  the 
volution  seen  in  PI.  I,  fig.  4.     These  faint  undulations  are  due  to  prolonga- 
tions of  the  costfe  that  pass  between  the  tubercles  on  the  ventro-lateral 
angles.     This  keel,  which  is  a  mere  angle  on  the  venter,  was  obviously 
continuous  before  the  costaj  appeared  and  is  practically  continuous  sulise- 
quently,  owing  to  the  minute  character  of  the  inflections.      Upon  the  last  of 
the  outer  volution  at  this  diameter,  the  first  of  the  fourth  volution,  the  outer 
line  of  tubercles  appears  and  is  connected  by  costse  with  the  inner  line. 
The  last  are  very  widely  separated  at  first  and  become  nearer  only  in  later 
stages.     The  larger  costse  at  this  age  are  separated  by  single,  arcuate  costa- 
tions  terminated  outwardly  by  minute  tubercles  and  fading  out  internally 
about  halfway  across  the  volution.     The  umbilical  zones  are  not  diff"erenti- 
ated  from  the  sides.     The  side  is  evenly  plano-convex  from  the  keel  to  the 
line  of  involution  and  the  inner,  uncostated  part  is  smooth,  excejit  where 
interrupted  by  the  inner  tubercles  or  extensions  of  the  tubercular  termina- 
tions of  the  larger  costse.    The  tubercles  and  nodes  are  opposite,  not  alternate. 
The  sutures  at  this  age  consist  of  two  large  saddles  (PI.  I,  fig.  9),  a  narrow  first 
lateral  lobe  in  the  center  of  the  lateral  zone  and  a  broad  second  lateral  on  the 
umbilical  zone.     The  inflections  are  all  apparently  entire.     In  succeeding 
stages  the  lobes  remain  in  the  same  position,  there  being  but  one  in  the 
center  of  the  side  between  the  two  rows  of  tubercles  and  one  on  the  umbilical 
shoulder,  but  as  the  shoulder  becomes  more  prominent  and  the  umbilical 
zone  broadens,   other  lobes   and   saddles   appear  internally.      The  venter 
broadens  Avith  age,  the  keel  becoming  more  obscure  in  consequence  of  this; 
the  sides  become  flat  and  convergent ;   and  the  umbilical  shoulders  broaden 
out  more  than  the  venter,  the  increase  in  the  umbilical  zones  making  the 
umbilici  very  deep.     The  keel  on  the  cast  at  this  mature  stage  is  faintly 
undulated,  and  the  lateral  eostje,  although  very  obscure,  cross  the  venter 
and  inteiTupt  the  keel  between  each  pair  of  opposing  ventro-lateral  nodes. 
These  widely  separated  serrations  are  so  faint  on  the  cast  that  they  entirely 
escaped  my  observation  on  former  occasions.     They  in  fact  can  be  felt 
more  easily  than  they  can  be  seen.     This  is  also  the  case  in  the  earlier 
stages  described  above.     The  inner  nodes  are  always  larger  and  fewer 
than  those  on  the  edges  of  the  venter.     The  second  lateral  saddle  remains 
broader  than  the  first  lateral,  even  when  the  shell  is  somewhat  over  40  mm. 
in  diameter.     It  occupies  a  trifle  more  than  half  of  the  side  and  encroaches 
on  the  umbilical  zone  (PI.  I,  fig.  8). 


BUCHICERATID.E.  29 

The  ventral  lobe  is  very  widely  open  at  the  base  and  long-er  than  tlie 
first  lateral  lobe.  The  two  arms  are  blunt  and  ver}'  small.  The  siphonal 
saddle  is  phenoraenallv  short  and  broad,  with  a  faint  centran  marginal  lobe 
and  an  equally  faint  marginal  rounded  saddle  on  either  side.  The  first 
lateral  lobe  is  funnel  shaped,  broad  at  the  base,  short  and  narrowing 
rapidly  to  a  bifid  termination.  Tlie  second  lateral  lobe  is  very  much 
smaller  and  shorter,  and  entire  at  the  end.  The  third  lateral  saddle  is 
small,  entire  until  a  late  stage,  but  becoming  bifid  later.  Beyond  are  two 
small  entire  saddles  and  two  corresponding  lobes  or  what  may  perhaps  be 
more  accurately  described  as  a  bifid  lobe  and  a  bifid  saddle. 

The  first  and  second  lateral  saddles  have  internal  ridges,  but  these 
coalesce,  forming-  a  short,  flattened  area  along  the  mesal  plane,  which 
becomes  deeply  convex  toward  dorsum  and  venter.  There  are  only  two 
broad  saddles  and  two  naiTow  lobes  on  the  dorsum,  and  these  have  no 
connecting  ridges  Avith  the  external  saddles.  The  surfaces  of  the  wings  of 
the  septa  are  strongly  inclined  inward,  the  outer  sutures  being  considerably 
in  advance  or  orad  of  the  inner  ones.  This  gives  a  remarkably  concave 
aspect  to  the  wings  of  the  septa  on  either  side  of  the  dorsum. 

The  dorsal  sutures,  which  were  woi'ked  out  Avith  difficulty,  show  that 
the  inner  arm  of  the  bifid  fourth  lateral  saddle  passes  across  the  line  of 
involution,  coalescing  with  the  third  dorsal  saddle.  The  antisiphonal  lobe 
is  asymmetrical,  entire  at  the  top,  unequally  serrated  on  the  sides,  and  bent 
over  to  the  left  until  the  tips  touched  the  inner  angles  of  the  first  pair  of 
dorsal  saddles  to  the  right  of  the  mesal  plane  of  the  body.  The  first  pair 
of  dorsal  saddles  are  deep  and  broad  with  broad  entire  bases.  The  first 
lateral  lobes  are  small  and  unequally  bifid,  the  sides  being  coarsely  serrated. 
The  second  dorsal  saddles  are  much  inclined  and  obscurely  tridentate  or 
entire.  The  second  dorsal  lobe  is  very  small  and  entire.  The  third  dorsal 
saddle  is  a  part  of  the  fourth  lateral,  as  stated  above,  and  is  entire. 

Vestiges  of  the  shell  were  present  upon  this  cast  in  a  few  places  and 
showed  coarse  lines  of  growth.  Unfortunately  the  shell  covering  the  venter 
f)f  the  young  whorl  w^as  chipped  off  in  cleaning  this  part  for  drawing,  and 
evidence  of  the  statement  made  above  with  reference  to  the  keel  was  lost. 

Locality:  Cachiyacu,  west  side  of  Hullagua  River,  Peru. 

Age:  Upper  Cretaceous. 


30  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

ROEMEROCERAS  Hyatt. 

These  shells  were  so  similar  to  the  type  of  BiicMceras  in  external  aspect 
that  I  formerly  supposed  the  type  of  this  o-enus  to  be  an  older  stage  of  B. 
bilohatum,  but  more  prolonged  acquaintance  with  these  forms  shows  that 
they  are  not  in  the  same  generic  group.  While  the  bifurcated  costfe,  the 
large  nodes  on  the  umbilical  shoulders,  and  the  nodes  on  the  ventro-lateral 
angles  are  the  same,  the  involution  is  greatei",  the  lateral  zones  more  com- 
pressed and  broader,  the  umbilici  narrower,  the  young  have  larger  nodes, 
and  the  keel  entirely  disappears  in  the  full-grown  shells,  except  perhaps  in 
R.  (jabhi.  The  sutures  are  also  quite  distinct,  and  similar  to  those  of  Tisso- 
tidse  in  some  species,  but  the  first  latei'al  saddles  tend  to  develop  three  arms 
in  some  species  and  the  leases  of  the  other  saddles  are  apt  to  be  dentated 
more  or  less  completely.  The  ventral  lobes  are  similar  to  those  of  Buchi- 
ceras  and  entirely  distinct  from  the  broad  veutrals  of  the  Tissotiidai.  The 
same  characters  appear  to  unite  Knemiceras  with  Roemeroceras,  but  the 
development  and  full-grown  shell  in  Knemiceras,  especially  the  invariable 
presence  of  the  concave  venter,  seemed  to  place  it  in  closer  association  with 
the  Pulchelliidse. 

RoEMEROCEKAs  GABBi  n.  sp.  Hyatt. 

PI.  11,  %s.  1-3. 

Ammonites  hilobatu^  Gabb,  1877,  Jour.  Acad.  Nat.  Sci.  Philadelphia,  2d  .ser.,  Vol. 
VIII,  p.  270,  pi.  38,  fig.  3. 

In  my  i-evision  of  this  form  I  made  too  great  allowance  for  the  possible 
variations  due  to  age,  and  misled  Professor  Gabb  in  identifying  this  fossil 
with  Buchiceras  hilobatum.  As  compared  with  B.  bilobafiDii,  the  nodes  on  the 
umbilical  shoulders  are  much  less  prominent  and  more  numerous  and  more 
closely  approximated,  the  venter  has  large  ridges  not  present  in  bilobafuiii, 
and  the  flatness  and  proportions  of  the  saddles  are  too  distinct  to  occur  in 
the  same  sjjecies,  even  though  allowance  be  made  for  the  sutures  in  f/abbi 
being  nearly  one  volution  older  than  those  examined  in  B.  bilobatum.  The 
sutures  of  this  species  approximate  more  closely  to  those  of  R.  syriaciforme 
than  to  those  of  any  other  species,  but  R.  f/abbi  differs  in  the  greater  numljer 
and  smaller  size  of  the  nodes  and  costfe.  Fig.  3  of  Gabb's  plate  shows  the 
lateral  aspect  with  an  outer  line  of  nodes  lower  on  the  sides  and  a  sinuous 
outline  to  the  venter  which  does  not  appear  ni  syriaciforme,  and  also  a 


BUCHICERATID.E.  31 

stouter  and  more  quadrag'oiial  volution  than  any  other  species  of  this  genus. 
The  originals  of  this  species  were  not  reexamined.  They  could  not  be 
found  in  the  Academy's  collection  at  the  time  of  m^-  visits,  nor  has  subse- 
quent search,  made  by  the  kindness  of  Professor  Pilsbrv,  brought  them  to 
light. 

LocaUhj:   Quebrada  de  Colpamayo,  Department  of  Cajamarca,  Peru. 

Aye:   Upper  Cretaceous. 

ROEMEROCERAS  SYRIACIFORME  Hyatt. 
PI.  I.  figs.  10-14. 

Eoetnei'oceras  ^yriaciforme  Hyatt,  1875,  Proc.  Boston  See.  Nat.  Hist.,  Vol.  XVII 
p.  371. 

This  species  reaches  a  diameter  of  90  mm.  in  one  cast  without  a  living 
chamber.  The  sutures  ai-e  approximated  and  overlap  internally  on  the 
auxiliaries,  showing  that  the  geroutic  stage  has  begun.  The  ornamentation 
and  form  are  the  same  as  in  bilohatuin.  When  the  cast  is  only  29.5  mm.  in 
diameter  there  is,  however,  no  difficulty  in  separating  this  from  bilohatum. 
It  is  more  compressed,  the  sides  broader,  the  venter  narrower  and  flatter. 
The  sutures  have  more  resemblances  to  those  of  R.  (/ahbi,  but  the  saddles 
and  lobes  are  never  so  short,  nor  truncated,  the  saddles  being  narrower  and 
the  lobes  broader.  The  ventral  lobe  and  siphonal  saddle  are  similar,  but 
narrower  and  less  digitated.  The  first  lateral  saddles  are  similar  in  being 
bifid  and  rather  broad,  but  already  at  this  early  stage  sho^v  denticulations 
over  the  entire  base.  The  first  lateral  lobe  is  similar  but  less  deeply  divided, 
by  the  similar  marginals.  The  second  lateral  saddles  are  unequally  bifid 
s\'ith  bases  rounded  or  approximately  phylliform,  entire,  and  unlike  those  of 
(/ahbi  The  second  lateral  lobes  are  quite  broad,  a])ically  like  the  first 
laterals,  but  are  unequally  quadrifid.  The  third  lateral  saddle  is  as  broad 
as  the  second  lateral,  and  also  l^ifid.  It  occupies  part  of  the  side  and  also 
part  of  the  umbilical  zone,  the  marginal  lobe  being  upon  the  umbilical 
shoulder.  Inside  of  this  there  is  one  broad  bifid  saddle  reaching  to  the 
lobe  at  the  line  of  involution.  There  are  therefore  four  saddles  at  this  early 
stage  very  like  those  of  yabbi,  except  in  having  rounder  bases.  Later,  on 
the  same  volution,  this  inner  saddle  becomes  divided  into  two  by  a  median 
marginal  lobe,  and  still  later  a  small  lobe  makes  its  appearance  at  the  line 
of  involution,  completing  the  outline  of  the  innermost  lateral  saddle. 
There  are  then  five  saddles  and  six  zygos  lobes  on  either  side. 


32         PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

The  oldest  svitures  are  very  much  changed,  and  look  like  those  of  a 
distinct  species,  but  are  obviously  in  the  gerontic  stage.  The  bases  of  the 
saddles  are  nearer  together,  the  entire  parts  of  the  sides  much  elongated, 
and  the  lobes  longer  and  narrower  and  the  dig-itations  situated  at  their 
apical  ends  nuich  deeper.  The  saddles  are  longer  and  broader,  with  entire 
bulging  sides,  and  the  marginals  not  increased  in  number,  but  much  longer 
and  larger. 

The  sutures  have  at  this  stage  close  similarity  to  the  peculiar  outlines 
attributed  to  Ammonites  syriaciis  by  von  Buch  (fig.  1  of  pi.  7  in  his  Uber 
Ceratiten),  but  the  first  lateral  is  not  so  broad  and  does  not  have  the  minute 
jjhylliform  marginals  of  that  figure.  The  marginals  on  the  first  lateral 
saddles,  and  also  in  the  first  lateral  lobe,  are  tongue  shaped. 

The  fourth  and  fifth  lateral  saddles  are  entire,  tongue  shaped,  and 
divided  by  a  narrow  bifid  lobe.  The  young  sutures,  until  a  late  neanic 
stage,  have  outlines  similar  to  those  of  some  species  of  Tissotia.  After  this 
the  outer  saddles  become  completely  denticulated,  and  again,  as  described 
above,  lose  a  considerable  part  of  these  denticles  in  old  age. 

Fragments  of  the  shell  were  present  on  the  largest  cast.  None  of  the 
specimens  was  incrusted  by  any  extraneous  growths  that  could  be  shown 
to  have  fastened  themselves  on  the  surfaces  of  the  casts. 

The  figure  of  the  young  in  an  early  ephebic  substage  (PI.  I,  fig.  12)  is 
a  very  near  approach  to  the  old  specimen  which  was  crushed  on  one  side 
(PI.  I,  fig.  10),  but  of  course,  owing  to  difterences  of  age,  the  nodes  are 
larger."  There  are  fifteen  nodes  on  the  ventral  border  and  six  on  the 
umbilical  shoulders  on  one  volution  of  the  younger  specimen,  and  eleven 
on  the  outer  and  seven  on  the  inner  row  of  the  old  specimen.  The  bifid 
costfe  are  also  present  in  the  younger  specimen,  mingled  with  single  ones, 
as  in  the  old  stage.  The  keel  disappears  on  the  last  quarter  of  the  outer 
volution,  both  on  the  cast  and  on  the  shell,  in  the  young  specimen,  and  is 
absent  also  in  the  older  one.  The  young  shell  was  seen  in  a  section  of  the 
specimen  represented  by  fig.  12  of  PI.  I,  and  although  not  perfect  enough 
to  figure,  showed  that  when  about  of  the  same  size  as  the  young  of  B. 
hilohatum  (PI.  I,  figs.  5,  7),  it  had  a  similar  keeled  form. 

Locality:  Cajamarca,  Peru. 

Age:  Upper  Cretaceous. 

"See  also  description  of  /<!.  attenuatuin  Hyatt. 


BUCHICERATID.E.  33 

ROEMEROCERAS    ATTENUATUM    (Hyatt). 

PI.  1.  tig.  15. 

Buchic&i'as  attewuatuni  (pars)  Hyatt.  1S75,  Proc.  Boston  Soc.  Nat.  Hist.,  Vol.  XVH, 
p.  372. 

The  oast  differs  from  syriaciforme  in  having  more  numerous  nodes  on 
the  inner  hne.  On  the  outer  vohttion,  at  a  diameter  of  64  nun.,  there  are 
about  nine  on  the  inner  row  and  sixteen  on  tlie  outer,  whereas  in  syriaci- 
forme^ at  a  diameter  of  90  nnn.  there  are  seven  on  tlie  inner  hne  and  eleven 
on  the  outer  hne;  in  another  specimen  of  syriaciforme,  at  a  diameter  of 
73  mm.,  there  are  the  same  number;  in  another,  at  a  diameter  of  34  mm., 
there  are  six  on  the  inner  and  fourteen  on  the  outer  hne;  in  another,  at  a 
diameter  of  41  mm.,  there  are  seven  on  the  inner  hne  and  fifteen  on  the  outer. 

There  are  faint  signs  of  a  keel  on  the  type  specimen,  showhig  that  it 
belongs  in  this  genus.  The  general  form  is  nmch  more  compressed  than 
that  of  R.  syriaciforme ;  the  venter  is  narrower  and  the  keel  is  also  less  devel- 
oped. The  volutions  are  more  enveloping,  and  the  umbilicus  is  smaller. 
The  specimen  is  a  cast,  partly  crushed  on  one  side  and  somewhat  worn  on 
the  other,  but  although  the  sutures  are  not  consequently  perfect  they  are 
entirely  distinct  from  those  of  other  species.  The  first  lateral  lobes  are  bifid 
and  shorter  than  the  ventral  lobe.  Instead  of  being  of  about  the  same 
length  or  longer  than  the  ventral,  as  in  R.  syriaciforme,  all  the  saddles  are 
broad  and  very  short,  as  are  also  the  lobes.  The  first  lateral  saddles  and 
lobes  are  completely  denticulated  by  marginals.  The  second  lateral  is  trifid, 
the  third  and  fourth  saddles  are  bifid,  and  there  is  a  fifth  saddle,  but  this  is 
on  the  line  of  involution  and  very  narrow.  The  second  lateral  lobes  are 
trifid.  Tlie  third  lobe  is  in  the  umbilical  zone  and  bifid,  but  otherwise  entire, 
and  the  fourth  is  very  small  and  apparently  entire,  but  too  mitcli  worn  td 
make  observation  certain. 

There  are  incrusting  ostreans  upon  botli  sides  of  this  cast  and  they 
appear  to  have  been  attached  to  a  fossil  cast. 

This  species  is  founded  upon  a  single  fossil  cast,  one  of  the  two  used 
for  the  description  of  Buchiceras  attenuatum  Hyatt,  but  not  the  type.  The 
latter  is  to  be  found  on  page  151,  imder  the  name  of  Knemiceras  attenuatum 
Hyatt. 

Locality:  Celendin,  Peru. 

Age:  Upper  Cretaceous. 

MON  XLIV — 03 3 


34         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

ROEMEROCERAS    SUBPLANTM    11.  Sp.  Hyatt. 

PI.  TI.  figs.  J-t'.. 

This  specimen  is  a  cast,  whole  diameter  5.5  mm  The  lateral  zones 
are  flatter  than  in  B.  syriaciforme  and  denticulatum,  and  the  outer  nodes  are 
smaller,  more  acute,  and  have  slight  ridges  or  orad  continuations  in  some 
cases.  The  inner  nodes  are  also  smaller  in  the  young  and  increase  very 
rapidly  in  size  on  the  last  volution  and  then  suddenly  disappear,  the  volution 
becoming  at  the  same  time  contracted  to  a  subquadrate  outline.  There 
are  four  small  and  three  large  nodes  on  the  inner  line,  the  place  where  the 
fifth  node  ought  to  be  is  vacant,  and  there  are  fifteen  nodes  on  the  outer 
line.  The  living  cliamber,  which  is  probably  very  nearly  complete,  is  less 
than  one-half  of  a  volution  in  length  The  last  two  large  nodes  of  the 
inner  line  are  on  this  chamber. 

The  sutures  have  very  broad,  short,  simple  saddles  and  ver}^  short 
lobes.  They  are  similar  to  tliose  of  B.  denticulatum  but  have  not  sucli 
complex  outlines.  The  last  six  sutures  are  nearer  together  and  become 
finally  closely  approximated,  showing  that  the  fossil  is  probably  an  out- 
grown shell.  This  cast  having  been  cracked  open,  it  was  possible  to  study 
exactly  the  contact  of  incrusting  ostreans  with  the  surface.  It  was  found, 
as  in  other  cases  described,  that  no  shell  layers  were  present,  the  ostrean 
having  grown  directly  upon  the  surface  of  a  fossil  cast.  The  shell  is 
present  in  the  impressed  zone  where  it  is  jjrotected  by  the  enveloping 
volutions,  and  it  is  there  thick  and  well  defined. 

Locality:  Cajamarca,  Peru. 

Age:  Upper  Cretaceous. 

PSEUDOTISSOTIIDiE  Hyatt. 

If  the  position  here  taken  is  correct,  the  genera  assembled  under  this 
name  are  distinct  from  those  heretofore  included  under  the  Tissotiida? 
Thev  include  forms  from  the  discoidal  channeled  and  keeled  Pseudotissotia 
in  the  Turonian  to  the  highly  involute  compressed  Plesiotissotla  of  the 
S'enonian.  The  lobes  have  the  same  denticulated  outlines  as  in  Tissotidae, 
but  the  saddles  are  more  complex,  being  denticulated  in  all  the  genera 
except  Plesiotissotla,  in  which  they  are  all  bifid,  the  first  lateral  saddles 
being  quadrifid  according  to  Peron's  figure. 


PSEUDOTISSOTIID.E.  35 

The  relations  of  the  genera  in  this  family  can  only  be  estimated  by 
their  fiill-grown  shells  and  sutures,  and  doubtless  any  arrangement  that 
can  now  be  made  will  be  only  provisional.  So  far  as  the  facts  go, 
PseudotissoHa  is  a  flat-ventered,  keeled,  and  clianneled  form  until  a  late  age, 
losing  its  keel  in  old  age  and  having  so  close  a  resemblance  to  Tissotia 
tissoti  that  it  seems  to  be  the  only  form  having  any  claims  to  be  considered 
the  aucest(  >r  .  if  that  species,  as  first  pointed  out  by  Peron. 

Choffaticeras,  until  a  late  age,  has  a  venter  with  keel  and  channels  like 
those  of  Pseudofissotia  in  C.  meshi  but  combined  with  an  inflated  volution 
and  deep,  abrupt  umbilici  and  highly  inclined,  convergent  sides.  In  other 
species  the  line  of  modifications  indicated  by  the  later  stages  of  its  ontogeny 
leads  into  forms  having  subacute  venters  at  a  comparatively  early  age,  and 
possibly  the  keeled  and  channeled  stage  with  its  flat  venter  may  have 
altogether  disappeared  in  some  of  these.  The  highly  involute,  comi)ressed- 
keeled  forms  of  Hemitissotia  follow  these  in  the  same  line  of  modification 
and  as  their  sutures  also  coincide  and  they  occur  in  the  Senonian,  whereas 
all  of  the  above-described  genera  are  Turonian,  Peron's  idea  that  they  are 
the  direct  descendants  of  Pseudotissofki  seems  to  be  well  sustained. 

That  these  are  not  transitional  to  true  Tissotia  becomes  apparent  when 
It  IS  recognized  tliat  tlie  type  form  of  tliat  genus  has  an  ontogenetic  history 
like  that  of  PseudotissoHa  and  is  probably,  as  stated  in  the  description  of 
the  Tissotiida",  the  most  primitive  member  of  a  series  of  forms  distinguished 
by  their  differences  of  development  as  well  as  by  tlieir  simpler  and  more 
retrogressive  sutures. 

Although  the  sutures  differ  decidedly,  the  forms  of  more  i)rimitive 
species  like  Pseadotissotia  yallienmi  and  their  keels  appear  to  place  thein 
provisionally  nearer  to  the  Buchiceratida?  than  to  the  keelless  forms.  I  have 
had  no  fossils  for  examination  in  this  family,  but  the  literature  and  the 
figures  given  by  Grossouvre  and  Peron  have  been  sufficient  to  enable  me 
to  arrange  the  forms  provisionally  and  to  make  connnents  upon  their 
probable  relations  that  will,  it  is  hoped,  attract  attention  and  lead  those 
who  have  better  opportunities  to  test  the  truth  of  the  views  presented 
below. 

PSEUDOTISSOTIA  Peron. 

Peron's  typical  species,  Ps.  fjaUiennei,  is  a  discoidal  form  with  keel  and 
channels,  having  obviously,  as  observed  by  Peron,  genetic  affinities   with 


36         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

true  Tissotia  as  here  defined,  but  it  differs  in  the  more  complex  outHnes  of 
the  sutures,  all  of  which  have  small  marginal  lobes  and  saddles.  In  my 
opinion,  the  genus  should  be  limited,  so  far  as  known,  to  one  species,  the 
type  described  bv  Peron.  The  other  species  described  under  this  name  are 
obviously  widely  distinct  in  their  forms  and  mode  of  development.  The 
sutures  resemble  those  of  Boemeroceras  on  the  lateral  aspect.  The  ventral 
lobes  are  also  alike,  so  far  as  can  be  seen  on  Pei'on's  figure.  Peron's  sug- 
srestion  that  these  are  the  ancestors  of  Tissotia  and  its  allies  in  the  Senoniau 
appears  to  be  supported  by  the  facts  so  far  as  now  known.  They  appear 
also  to  have  been  the  immediate  ancestors  of  Henutissotia  and  its  allies  iu 
the  Senoniau,  but  this  last  inference  needs  confirmation  that  can  only  be 
obtained  through  the  study  of  the  young  of  the  latter. 

PSEUDOTISSOTIA     GALLIENNEI     (d'OrljigUy). 

Psmdotissotia  gallimnei  Peron.  1896,  Mem.  Soc.  geol.  France.  Paleontologie,  Vol. 
VI,  No.  17.  pi.  2.  tig.  3:  pi.  3.  tig.  1. 

This  is  a  moderately  compressed  but  still  comparatively  discoidal  form, 
with  large  umbilicus  and  involution  enveloping  something  more  than  one- 
half  of  the  sides,  according  to  Peron's  figures.  The  venter  is  flattened, 
with  heavy,  continuous  keel  and  shallow  channels  bordered  externally  l)y 
thick  continuous  ridges.  The  sides  have  very  broad  fold-like  costae  with- 
out tubercles.  In  extreme  age  all  of  these  ornaments  disappear.  The 
entire  aspect  and  genetic  transformations  of  this  fossil  are  so  similar  to 
those  of  Tissotia  tissoti  that  it  would  have  to  be  included  in  the  same  genus, 
if  the  sutures  were  unknown. 

Locality:  France. 

Age :    Turonian. 

PsEUDOTissoTiA  '?  TUNisiENSis  n.  sp.  Hyatt. 

Tissotia  cf.  fourneli  Peron,  1896.  Mem.  .Sue.  geol.  France.  Paleontologie,  \o\.  VI. 

No.  17,  pi.  12,  tigs.  7,  8. 
Tissotia  fournel !  Peron.  1890,  Moll.  Cret.  de  la  Tunisie.  ])1.   17.  tigs.  11-18. 

This  remarkable  fragment  has  a  truncated  ventei",  entire  keel,  and 
compressed  volution,  with  moderately  large  umbilicus.  The  costte  are  fold- 
Hke,  with  tubercles  on  the  umbilical  shoulders  and  a  line  of  closely  set 
elouffated  tubercles  on  the  ventro -lateral  angles.  The  first  lateral  saddles 
are  trifid  and  rather  peculiar,  owing  to  the  approximate  equalit}'  of  the  tliree 


PSUEDOTISSOTIID.E.  37 

marginal  saddles.  The  other  saddles  are  very  long-  and  phylHfonn,  and 
according-  to  Peron's  tig-nres  the  third  saddle  is  tritid  or  bifid.  These 
sutures  and  the  ventral  lobe,  with  its  steep  denticulated  sides  and  truncated 
siphonal  saddle,  are  similar  to  the  sutures  of  the  old  stage  of  Roemeroceras 
syriaciforme.  The  form  and  ornamentation  also  agree  with  this  determina- 
tion, but  the  keel  is  more  prominent  than  is  usual  in  this  genus.  It  is  pos- 
sible to  understand  this  form,  if  it  is  related  to  Ps.  (jaUiennei,  because  in  that 
case  the  keel  and  lateral  costse  are  similar  to  those  of  that  species.  The 
differences  in  sutures  lie  largely,  according  to  Peron's  figure,  in  the  second 
lateral  saddles,  which  are  entire.     This  mav  be  due  to  retroo-ression. 

Locality:  North  Africa. 

Age:   Santonian. 

CHOFFATICERAS  n.  gen.  Hyatt. 

This  genus  has  sutures  similar  to  those  of  Pseudotissotki,  but  the  form 
is  distinct.  The  species  are  more  or  less  stout  gibbous  forms  with  more  or 
less  open  and  deep  umbilici.  The  sides  are  heavily  costated  and  nodose 
along  the  umbilical  shoulders,  but  there  are  no  external  tubercles  according 
to  Peron.  He  also  describes  the  venter  as  liaving  a  continuous  keel  and 
two  ventro-lateral  ridges.  The  form  is  more  involute  and  more  compressed 
than  Pscudotissotia,  and  the  outer  parts  of  the  volutions  have  a  tendency  to 
become  concave  in  the  involute  species  with  broad  volutions. 

The  type  is  C.  meslei  (Peron). 

(Jhoffaticeras  barjonai  (Chofiat). 

Pseudvtlsiiotla  haijoaal  Choffat,  1898,  Faune   Cret.  du  Portugal,  Vol.  I,  2d  series, 
pi.  18,  fig-.  3;  pi.  22,  figs.  40-42. 

This  species  is  a  close  ally  of  C.  meslei  of  North  Africa,  as  has  been 
stated  by  Choffat,  l)ut  has  a  more  i)rominent  keel  and  has  no  signs  of 
channels  on  the  venter. 

Locality:  Portugal. 

Aye:  Turonian. 

Choffaticekas  meslei  (Peron). 

P^cudotlnxutlii  iiiKsIel   Peron  (i^ars),  189ij,  Mem.    Soi-.   geol.   France,  Paleontologie, 
Vol.  VI,  No.  17,  pi.  1,  fig-.  1;  pi.  2,  fig.  1  (not  pi.  2.  fig.  2.  nor  pi.  3.  fig.  2). 

This  species  has  a  form  which  is  sublenticular  when  seen  from  the 
front  in  Peron's  figure,  owing  to  tlie  great  prominence  of  the  umbilical 


38         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

shoulders  and  the  rapid  wlope  of  the  latei-al  zones  and  subacute  character 
of  the  venter.  Tlie  costaj  are  hnear  and  only  slightly  curved  in  the  nnly 
well-preserved  part  of  his  type  as  fio-ured.  The  involution  covers  about 
three-fifths  of  the  next  inner  whorl,  leaving-  a  rather  large  open  umbilicus 
showing  the  younger  whorls. 

The  more  discoidal  form  (\A.  2,  fig.  2,  and  pi.  3,  fig.  2)  supposed  to 
belong  to  this  species,  is  certainly  distinct  specifically  and  may  be  nearer 
to  Pseudotissotia  tlian  to  any  species  of  this  genus,  but  it  is  too  imperfect  to 
g-ive  diag-nostic  characters. 

Locality:  North  Africa. 

Age:  Tnronian. 

Choffaticeras  ?  DOuviLLEi  (Peron). 

Pseudotissotia  douvillei  Peron,  189*;,  jNleiii.  Soc.  geol.  France,  Paleontologie,  Vol. 
VI,  No.  IT,  pi.  2,  figs.  4:,  5,  and  pi.  3,  figs.  3,  4. 

This  species,  as  figured  and  described  by  Peron,  has  the  general  form 
and  aspect  of  C.  meslei,  but  the  heavy  nodes  on  the  umbilical  shoulders 
and  dichotomous  costai  reaching  to  the  sides  of  the  prominent  keel  are 
quite  difierent. 

Locality:  North  Africa. 

Aye:  Tnronian. 

HEMITI8S0TIA  Peron. 

This  "enus  seems  to  me  to  be  more  intimately  related  to  Choffaticeras 
than  to  Tissofia  and  other  genera  having  similar  forms  lint  having  sutures 
with  smooth  saddles.  Such  questions  can  only  be  definitely  settled  when 
the  younger  stages  become  known.  These  involute  and  more  or  less  com- 
pressed forms  with  trenchant  keeled  venters  are  apparently  in  the  direct 
line  of  modifications  indicated  by  the  sinnlar  forms  of  Tissotida?,  but  on 
the  other  hand  their  sutures  correlate  with  the  more  complex  outlines  of 
those  of  Psendotissotia  and  Choffaticeras,  and  this  indicates  that  the}-  are 
simply  parallel  as  representative  forms  analogous  to  some  of  tlie  Tissotidse 
but  reall}'  in  the  genetic  line  of  Choffaticeras.  They  have  retrogressive 
characters  in  the  undivided  outlines  of  their  inner  saddles,  but  this  arrest 
of  development  has  not  affected  the  outer  saddles  that  are  completely 
dio-itated.  They  can  not  be  placed  anywhere  in  the  genetic  line  lietween 
Pseudotissotia  .and  Subtissotia  on  account  of  the  absence  of  channels  and 


PSEUDOTISSOTnD.E.  39 

ridges  on  either  side  of  the  keel,  and  tliis  is  the  only  position  that  could  be 
claimed  for  them  in  view  of  their  peculiar  sutures.  All  of  their  characters 
accord  best  with  the  view  that  they  are  direct  descendants  of  Choff'aticeras. 
There  is  an  interesting-  group  of  this  or  an  allied  genus  from  the  Senonian, 
described  by  Chotfat  in  liis  Cephalopodes  de  la  Faune  Cretacique  du  Portu- 
gal, Vol.  I,  2d  series,  but  the  condition  of  the  specimens  did  not  permit 
him  to  describe  them  sufficiently  to  judge  closely  of  their  affinities. 

Hemitissotia  cazini  Peron. 

Hemitissotia  cazini  Peron,  1897,  Mem.  Soc.  geol.  France,  Paleontologie,  Vol.  VII, 
No    17,  pi.  14.  tigs.  1-5;  pi.  IS,  figs.  9.10. 

This  species  is  a  highly  involute  compressed  form,  and  in  the  oldest 
specimen  tigured  the  first  and  second  lateral  saddles  are  completely 
denticulated,  the  third  is  equally  divided  by  a  median  marginal  lobe  in  the 
figure  of  the  suture  of  the  oldest  specimen  (pi.  18,  fig.  9),  but  this  is  not 
described  in  the  text. 

Locality:  North  Africa. 

Age:  Senonian. 

Hemitissotia?  batnensis  Peron. 

Hemitissotia?  hatnensis  Peron,  l.S!)7.  Meiu.  Soc.  geol.  France,  Paleontologie,  Vol. 
VII,  No.  17.  pi.  l.T.  tigs.  7,  s. 

This  species  has  the  external  aspect  nf  this  peculiar  group  and  the 
sutures  are  similar  as  figured  by  Peron,  but  his  question  mark  after  the 
generic  name  is  justified  by  the  S2)henodiscus-\ike  aspect  of  the  first  lateral 
saddles. 

Locality:   North  Africa. 

Age:  Senonian. 

Hemitissotia  morreni  (Coquand). 

Hemitissotia  morreni   Peron  (pars),  1897,  Mem.  Soc.  geol.  France,  Paleontologie. 

Vol.  VII,  No.  17,  pi.  15,  figs.  1  and  2  only,  and  pi.  is.  tig.  11. 
neiiiitinsotki  morre^ii  v&T.  prsecipua,  ibid.,  p.  77. 

This  var.  prcecipua  of  Peron  is  a  highl}'  compressed  form  with  acute 
venter.  PI.  15,  fig.  8,  may  be  the  young  of  this  species,  and  if  so,  it  shows 
conclusively  that  it  is  distinct  from  the  following. 

Locality:  North  Africa. 

Age:  Senonian. 


40         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

HeXIITISSOTIA    TISSOTI.EFORMIS    Peroii. 

ILiidtisHotla   morreni  var.   tmot'neforiiili<  Peron,  1897,   Mem.    Soc.    geol.   France, 
Pal^ontologie,  Vol.  VII,  No.  17.  pi.  15,  figs.  -3-5  only. 

This  i.s  a  much  stouter  form  with  stouter  volutions,  and  as  might  lie 
expected  in  such  a  species  the  young  exhibits  distinct  ribs.  Hemitissotia 
morreni  var.  coquandi  (pi.  15,  fig.  6)  may  be  distinct,  but  no  front  view  is 
given  and  the  sutures  shown  in  pi.  18,  fig.  14,  do  not  appear  to  be  very 
different. 

Locality:  North  Africa. 

Age:  Senonian. 

Hemitissotia  d.ielfensis  (Peron). 

Tissotia  djelfemis  Peron,  1897.  Mem.  Soc.  geol.  France,  Paleontologie,  Vol.  VII. 

Mo.  17,  pi.  It),  figs.  3,  4. 
Buchiceras  ewaldi  (pars)  Peron,  i8yiJ,  Moll.  Cret.  de  k  Tunisie,  pi.  15,  figs.  7  and  9 

(no  others). 

This  is  a  compressed  shell  very  closely  allied  to  Paratissotiajicheuri  in 
aspect,  but  differing  in  the  sutures.  These  have  the  first  lateral  saddles 
narrow  and  bifid  as  in  Hemitissotia  and  the  first  lateral  lobe  is  large  as  in 
that  genus.  The  figure  of  the  highly  compressed  cast  given  by  Peron  as 
part  of  his  ewaldi  in  the  MoUusques  Cretace  de  la  Tanisie  has  very  similar 
sutures  so  far  as  the  deep  division  of  the  first  lateral  saddles  and  lobes  is 
concerned.  It  is  better  to  quote  it  here,  since  it  is  undoubtedly  not  related 
to  tlie  other  species  on  the  same  plate  and  has  also  a  form  similar  to  that  of 
djelfensis. 

Locality:  North  x\frica. 
Age:  Lower  Senonian. 

Hemitissotia  ceadouroensis  Choffat. 

Hemitissotia  ceadouroemis  Choflat,  18!»8,  Faune  Cret.  du  Portugal.  Vol  I.  2d  series, 
pi.  20,  tigs.  7-10. 

This  species  is  apparently  a  member  of  this  genus  and  is  of  interest 
in  sliowing  the  old-age  transformations,  the  rounding  of  the  venter  and 
contraction  of  the  outer  volution.  If  the  last  part  of  the  last  volution  is 
perfectly  natural,  it  shows  an  extraordinary  senile  scaphitoid  deviation  from 
the  spiral. 

Locality:   Portugal. 

Age:  Senonian. 


PSEUDOTISSOTIULE,  TISSOTIID.E.  41 


PLESIOTISSOTIA  I'eron. 


This  g-enus  lias  been  founded  by  Peron  entirely  upon  tlie  diti'erences  of 
the  sutures  as  compared  with  HeinUissot'm.  The  fii'st  hxteral  saddles  are 
broad  and  very  deeply  divided  by  a  median  maro'inal  lobe  and  each  arm 
is  plivlliforin  and  is  also  subdivided  by  a  median  marginal  lobe;  the 
remaining  saddles  are  phylliform  and  equally  subdivided  by  median 
marginal  lobes.  It  is  a  question  whether  these  peculiar  sutures  really 
represent  another  group  or  are  simply  retrogressi^'e  modifications  in  the 
genetic  line  of  Heinitissotia.  The  compressed  and  costated  form  does  not 
indicate  affinities,  but,  as  stated  by  Peron,  the  divided  saddles  are  similar 
to  those  of  Hemitissotia  prcBcipua,  except  the  first  laterals,  which  are  narrow 
and  irreffular  in  outline  in  the  latter. 


^e 


Plesiotissoti.1  michaleti  Peron. 

Ple-sintlssotui    iiiichaJcti  Peron,   1SH7,  Mem.   Soc.  g-eol.   France,  Paleontologie.  Vol. 
VII.  No.  17.  pi.  lt>.  tigs.  7.  S. 

A  liiglilv  compressed  keeled  form  with  costa'  having  tubercles  on  the 
umbilical  shoulders,  as  in  some  species  of  Hemitissotia.  The  sutures  are 
described  in  the  notice  of  the  genus. 

Locality:   North  Africa. 

Age:  Senonian. 

TISSOTIID^  Hyatt. 

This  family  name  is  here  much  narrowed  in  its  application  as  compared 
with  what  it  was  in  n\y  chapter  on  Cephalopoda  in  Zittel's  Textbook.  It 
is  now  considered  applicable  to  a  series  of  genera  that  includes  only  Tissotia 
and  its  immediate  allies,  excluding  Pidchellia,  Psilotissotla  and  Lopholohites. 
The  genera  can  be  described  as  having  keeled  forms,  with  channels  only  in 
primitive  genera.  The  keels  have  a  crenulated  or  nodose  stage  in  a  number 
of  pi'imitive  genera,  but  are  continuous  in  the  flattened  forms.  Costfe  are 
present  in  tlie  globose  pi-imitive  forms  and  are  usuall}-  tuberculated,  and 
when  they  di.sa])))ear  the  nodes  are  apt  to  persist.  The  venters  lose  their 
keels  and  become  rounded  or  flattened  in  old  ag-e.  One  genus  has  a  hollow 
keel  {Paratissotki)  and  others  may  have  hollow  keels.  So  far,  however,  the 
only  fact  in  favor  of  this  is  the  presence  of  prominent  keels  on  the  shells 
that  have  no  corresponding  keel  elevations  on  the  casts.     The  sutures  are 


42         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

characteristic,  having'  simply  digitated  or  phyHiforin,  often  entire  or  bitid 

saddles  and  narrow,  often  club-shaped,  lobes  digitated  at  their  tops. 

The  first   lateral    saddles   are   usually  bifid,  but   in   some  forms   thev 

become   trihd.     In  these   cases  the   additional   saddles   are   added  on  the 

ventral   side   through   the   division    of   the   outer   arm   of   the   first   lateral 

saddle.     The  group  as  here  defined  is  confined  to  the  Lower  Senonian  in 

Eurojje,  and  the  South  American  representatives  are  probably  of  about  the 

same  age. 

TISSOTIA  Douville'. 

The  definitions  heretofore  given  of  this  genus  have  been  based  upon 
the  sutures  whicli,  according  to  the  views  here  advanced,  can  not  be  accepted 
when  not  correlatable  with  external  characters.  The  type  of  this  genus, 
T.  tissofi,  so  far  as  can  be  seen  from  the  side  view  given  by  Bayle  and  the 
front  view  bv  Douville',  is  luiique  in  having  a  considerably  inflated  form 
like  some  S2)ecies  of  Suhfissotia,  but  with  keel  and  ventral  channels  bordered 
bv  continuous  ridges,  and  in  the  extreme  gerontic  substage  a  truncated 
venter  without  either  keel  or  channels.  This  certainly  justifies  the  opinion 
of  Grossouvre  that  this  species  is  closely  related  to  Pseudotissotia  rjaUieiniei. 
According  to  the  views  here  advocated,  this  genus  is  a  direct  derivative  of 
gaUiennei  of  the  Turouian,  as  has  been  previously  suggested  by  Peron. 

TissoTiA  TissoTi  (Bayle). 

Buchiceras  tissoti  Bayle,  1878,  Expl.  de  la  Carte  geol.  France,  Vol.  IV,  pi.  40,  tig.  1. 
Tlssotia  tissoti'DonyiWQ,  1891,  Bull.  Soc.  geol.  France,  3d  ser..  Vol.  XIX,  p.  501,  tig.  1. 
Tissotia  f!f<sofifFeTon,  1897,  Mem.  Soc.  geol.  France,  Paleontologie.  Vol.  VII.  No.  17. 
pi.  12,  tig.  3. 

The  type  of  Bayle's  species,  which  is  also  the  type  of  his  genus 
Tissotia,  has  been  figured  by  him  in  side  view  and  by  Douville  in  front, 
from  the  same  type  in  the  Ecole  des  Mines,  Paris.  Douville  also  describes 
the  specimen.  It  is  therefore  plain  that  it  is  a  stout  form  without  any  very 
marked  nodes  and  is  flat  on  the  venter  in  its  gerontic  stage,  having  lost  its 
keel  on  the  last  part  of  the  outer  volution  according  to  Bayle's  figure, 
Avhich  is  natural  size,  and  also  Douville's  figure.  This  shell  also,  according 
to  Douville's  figure,  preserves  an  unusually  depressed  venter  having  keel 
and  shallow  channels  on  either  side  bordered  b}'  faint  ridges  or  carintv 
throughout  the  adult  stage.  The  loss  of  the  keel  is  correlated  with  loss  of 
the  gibbosity  of  the  sides,  these  becoming  flatter  and  more  convergent 
outwardlv. 


TISSOTIID.E.  43 

SUBTISSOTIA  n.  gen.  Hyatt. 

This  group  includes  a  number  of  the  species  heretofore  associated  with 
Tissotia  tissofi  on  account  of  the  sutures.  These  are  uuquestionabh'  similar 
in  the  simplicity  of  their  outlines,  but,  as  has  been  arg-ued  above,  this  fact 
can  not  be  considered  as  determinative  in  such  peculiar  retrogressive 
groups,  unless  correlatable  with  other  characteristics  and  especially  with  the 
changes  in  the  development  both  of  the  young  and  the  gerontic  stage. 

The  >'Ounger  stages,  so  far  as  known,  beginning  with  the  neanic  stage, 
have,  as  a  rule,  very  globose  forms  with  continuous  keels,  the  sides  are 
costated  and  terminate  outwardly,  with  tuliercles  that  form  raised  but 
discontinuous  ridges  on  either  side  of  the  keel.  The  venter  is  much 
broader  tlnui  tlie  area  included  within  these  lines  of  nodes,  except  in  the 
gerontic  stage,  when  it  narrows  down  to  the  same  limits  as  are  common  in 
Metatissofia.  The  keel  disappears  in  the  gerontic  stage  and  the  lateral 
costae  and  the  nodes  also  in  some  species,  according  to  Peron's  ligures, 
leaving  the  venter  more  or  less  rounded. 

Tvpe  is  Si(bfissofia  inflata  (Peron). 

SuBTISSOTI.\    INFLATA  (Perou). 

Tissotia  tissofi  var.  infiata  Pei-on.  18!>7.  JVIeui.  Soc.  geol.  France,  Paleontologie, 
Vol.  VII.  No.  17,  pi.  12,  %.  t;. 

The  figures  of  this  form,  given  b}-  Peron,  show  an  excessively  stout 
shell,  increasing  rapidly  in  transverse  diameters  by  growth,  with  an 
obtusely  subacute  venter,  prominent  keel,  and  slight  cliannels  on  either 
side,  bordered  by  ridges.  Peron's  figure  at  diameter  of  68.5  mm.  is  51  mm., 
while  the  figure  of  intermedia^  which  is  92  mm.  in  diameter,  is  53  mm.,  only 
3  mm.  wider  than  the  much  smaller  and  yoiauger  specimen  of  inflata.  Such 
differences  of  pro])ortion  do  not  occur  in  the  same  species  of  Anmionites. 

Locality:  North  Africa. 

Age:  Base  of  Senonian. 

SUHTISSOTIA    INTERMEDIA  (PerOu). 

Tissotia  tis.s<iti  var.  intiriiK-iJia  Peron,  ISKT,  Mem.  Soc.  geol.  France,  Paleontologie, 

Vol.  VII,  No.  17,  pi.  12,  figs.  4,  5. 
Tissotia  tissoti  var.  laevigata  Peron,  ilticL.  pi.  13,  figs.  1.  2. 

This  form  differs  from  inflata  in  having  much  less  gibbous  volutions  at 
the  same  age  and  a  more  acute  venter  at  all  stages. 


44         PSECDOCERATITES  OF  THE  CRETACEOUS. 

Locality:  Northern  Africa. 
Age:  Lower  Senoniaii. 

SuBTissoTiA  PEKoNi  11.  s|).  Hyatt. 

Bucliicems  cwaldi  Perou,  18'.»U.  Moll.  Cn't.  du  hi  Tuui-iie,  pi.  1.5,  fio-.s.  1,  3  (no  other). 
Tissotia  moaldi  Pei'on,  1897,  Mem.  Sec.  jjeol.  France,  Paleontologie,  Vol.  VII,  No. 

17.  p.  <>3. 

This  is  based  on  a  specimen  from  Tunis,  of  a  diameter  of  107  mm.  It 
is  figured  by  Peron  as  having  an  entire  keel  throughout,  although  the 
rounded  tubercles  on  either  side  of  the  ventro-lateral  angles  have  almost 
disappeared  at  a  stage  when  in  his  cwaldi  var,  africana  they  would  have 
become  elongated  and  very  coarse  and  the  keel  have  been  resolved  into 
elongated  tubercles.  The  venter  is  also  entirely  distinct  in  this  species,  in 
its  sharper  outline  and  more  prominent  keel.  These  features  are  also 
associated  with  jieculiar  sutures.  The  sutures  of  Tissotia  africana  have  a 
long,  well-defined  ventral  lobe,  the  sides  of  the  first  laterals  being  abrupt, 
whereas  in  this  fossil  there  is  a  very  .short,  ill-defined  ventral  lobe,  with  the 
sides  of  first  lateral  saddles  denticulated  and  sloping.  The  first  lateral 
saddles  are  deeply  divided  in  T.  africana,  while  in  this  the  division  is  not  so 
well  marked.  Tlie  resemblances  in  form  and  sutures  between  this  and 
T.  Icpviffata  show  that  they  are  closely  related. 

Locality:  North  Africa. 

Age :  Base  of  Senonian. 

SuBTissoTiA  AFRICANA  (Peron). 

Tmotia  ewaldl  var.  nfrivniia  Peron.  is'.t7.  Mt'ni.  Soe.  gvol.  France,  Paleontologie, 
Vol.  VII.  No.  17,  pi.  11.  tigs.  1-H. 

At  a  diameter  of  54  mm.  tlie  young  figured  by  Peron  is  a  very  gibbous 
form,  in  which  the  broadest  diameter  of  the  last  volution  measures  about 
39  mm.  The  keel  is  continuous  and  prominent  even  on  this  cast,  and  there 
is  a  line  of  prominent  tubercles  on  either  side  along  the  ventro-lateral 
angles.  In  the  aged  specimen,  figured  at  diameter  of  108  mm.,  these  have 
become  elongated,  find  the  sides  being  less  gibbous  the  venter  is  flatter,  and 
on  this  volution  the  keel  begins  to  disappear,  becoming  resolved  into 
elongated  nodes.  There  are  no  cost*  figured  on  these  casts.  Peron  con- 
siders tills  identical  with  Tissotia  rohini,  as  figured  by  Grossouvre,  but  rohii/i 


TISSOTllD.^.  45 

is  a  costated  aompressed  species  witli  a  continuous  keel,  even  in  extreme 
age,  after  the  d  isappearance  of  the  hnes  of  tubercles,  according  to  Grossouvre's 
figure.  His  eiraldi  is  similarly  figured  as  a  compressed  shell,  but  not  in 
extreme  of  age  apparently.  This  species  is  evidently  distinct  from  T.ewaldi 
figured  b}-  Peron  in  his  MoUusques  Crc^taces  de  la  Tunisie,  which  attains  a 
large  size,  and  at  an  advanced  age  still  has  an  entire  keel  and  rounded 
tubercles.  The  resemblance  of  the  young  of  this  species  to  the  more  mature 
stages  of  Suhtissotia  inflata  and  intermedia  is  apparent,  if  Grossouvre  is 
coiTect  in  his  assignment  of  the  smaller  casts  figured  to  this  species. 

Localiti/:  North  Africa. 

A</e:  Lower  Senonian. 

METATISSOTIA  n.  gen.  Hyatt. 

Following  out  the  system  adopted  in  these  pages,  it  becomes  obvious 
that  species  having  the  peculiar  development  of  Metaiissoiia  fournell  and 
rohini  can  not  be  associated  with  either  Tissotia  or  Suhtissotia.  The  entire 
ontogeny,  including  the  gerontic  stage,  of  these  highly  compressed  forms 
is  distinct  from  Tissotia  and  Siihtissotia  on  the  one  side  and  from  the  more 
accelerated  develoi)meut  of  Poratissotia  on  the  other. 

The  typical  ontogeny  begins  with  a  stage  having  a  compressed  smooth 
form  and  a  continuous  keel.  In  the  next  stage  there  is  a  more  or  less  trun- 
cated venter  having  also  a  continuous  keel,  but  with  nodes  at  the  termination 
of  costse  that  appear  on  the  sides,  and  nodes  also  on  the  umbilical  slioulders. 
In  the  gerontic  stage,  the  costse,  keel,  and  channels  finally  disppear,  leaving 
the  sides  smooth  or  ornamented  only  with  large  nodes,  and  the  venter  more 
or  less  angular. 

Metatissotia  foukneli  (Bayle). 

Biirli'icerm  fouimeli  Bayle,  ls78,  Expl.   de  la  Carte  geol.  France,  Vol.   IV,  pi.  -iO, 

fig.  ?,  (not  fig-.  4). 
Tissotia  fiiunitl!  Peron,  1890,  Moll.  Cret.  de  la  Tunisie,  pi.  15,  figs,  lo-l-t. 
Tissotia  f(iu rneVi  Peron,  1897,  Mem.  Soc.  geol.  France,  Paleontologie,  Vol.  VII,  No. 
IT.  pi.  1(1. 

The  development  has  been  determined  by  Peron  in  his  Ammonites  de 
I'Algerie,  cited  above.  In  the  figures  of  his  youngest  specimen,  which 
measures  about  30  mm.  in  diameter,  there  are  large  dichotomous  costae 
with  alternating  short  single  cost?e.     In  the  oldest  part  of  this  specimen  and  in 


46         FSEUDOCERATITES  OF  THE  CRETACEOUS. 

the  stage  represented  by  the  next  figure,  the  forks  of  the  dicliotonious  costfe 
are  becoming  obsolete  and  being  resolved  into  short  costse,  so  that  there  are 
two  short  nodose  costse  between  the  larger  ones.  This  is  obviou.sly,  how- 
ever, very  irregular,  since  in  the  figured  specimen,  which  has  a  diameter  of 
85  mm.,  there  is  still  one  dichotomoiis  costation.  It  is  obvious,  too,  that  the 
costa?,  being  very  heavy,  become  folddike  with  age.  The  longer  costse 
have  nodes  on  the  outer  ends  along  the  ventro -lateral  angles,  and  nodes 
along  the  umbilical  shoulders,  which  persist  throughout  the  ephebic  stage 
and  are  present  as  vevj  broad,  low  folds  in  the  gerontic  stage.  According 
to  Peron's  description  and  figures,  the  short  costse  disappear  and  are  appar- 
ent only  as  simple  nodes  in  large  specimens. 

This  is  a  compressed  form  of  this  genus  having  an  entire  keel  at  an 
early  stage,  and  a  close  ally  of  the  European  species  31.  nodosa.  Peron 
has  clearly  shown  that  Bayle  confounded  two  species  nnder  this  name,  but 
I  doubt  whether  Bayle's  Tissotia  fourneli,  figs.  4-5  of  pi.  40,  is  identical 
with  eivaldi. 

Locality:  North  Africa. 

Afie:  Base  of  Senonian. 

Metatissotia  robini  (Thiolliere). 

Ammonites  robini   Thiolliere,   1848,  Aim.    Soc.    crAgriculture  de    Lyon,   Vol.    XI. 

Pll- 
Buc/ucera-^  ewaldiYnMot,  1885,  Ann.  sci.  geoL,  Vol.  XVIII,  pi.  3,  tigs.  1,  2.? 

Ammonites   cfr.    ewaldi  Redtenbacher,  1873,    Abhandl.  K.-k.    geol.   Reichsanstalt, 

Vol.  V,  pi.  22,  figs.  5  a-i. 
Tissotia  rohiiii  Gros.souvre,  1893,  Ammonites  Craie   superieure.  pi.  4.  fig.   1  (not 

fig.  2  b). 
Tissotia  ewaldi  (pars)  Grossouvre,  i})id.,  pi.  0,  fig.  5. 

This  shell  has  a  compressed  form,  and  the  adult  figured  by  Grossouvre 
at  a  diameter  of  about  50  mm.  has  a  truncated  venter  with  prominent  elon- 
gated tubercles  on  the  ventro-lateral  angles  and  a  prominent  continuous 
keel.  At  the  end  of  this  volution,  or  say  at  a  diameter  of  55  mm.,  accord- 
ing to  Grossouvre's  figures,  these  tubercles  begin  to  disappear,  and  at  a 
diameter  of  80  mm.  they  are  absent,  and  the  venter  has  consequently  lost 
its  truncated  aspect  and  become  subacute.  This  agrees  also  with  Redten- 
bacher's  figure  of  a  specimen  which  is   83   mm.  in  diameter,  and  in  which 


TISSOTIID.E.  47 

the  old-age  characteristics   are  similar.     Grossouvre's  fig.  2,    also   named 

robini,  is  apparently  a  distinct  species.     It  has  the  subacute  venter  of  the 

oldest  oerontic  substage  of  true  robini  Avlien  only  59  mm.  in  diameter,  and 

this  beo'ius  when  the  shell  was  about  40  mm.  in  diameter  or  earlier,  accord- 
ed 

ing  to  this  figure.  This  whole  volution  is  also  covered  by  dichotomous  costaj 
having  only  very  faint  tubercles.  This  might  be  a  dwarf  of  this  species, 
but  is  appai'ently  not  a  young-  specimen.  Redtenbacher's  figures  (excejDt 
perhaps  5,  f  and  h)  all  appear  to  belong  to  this  species,  and  fig.  5f  may 
have  been  a  worn  s})eciinen  or  a  dwarf.  At  anv  rate,  the  latter  has  a 
suture  with  the  first  lateral  saddles  looking  remarkably  like  an  immature 
stage  of  those  characteristic  of  robini.  Grossouvre  thinks  this  is  the  true 
ewaldi  of  Buch,  but  on  the  contrary  it  seems  to  me  more  likely  that  part  of 
his  eivaldi  as  given  above  belongs  to  robini.  The  peculiar  ventral  trend  of 
the  outer  divisions  of  the  first  lateral  saddles  occurs  apparently  only  in  this 
species.  Redtenbacher's  figures  are  of  value  in  that  they  give  information 
with  regard  to  the  young,  showing  that  at  a  diameter  of  about  18  mm.  the 
keel  is  prominent  and  contiimous,  as  it  is  in  later  stages,  the  costte  are  well 
developed  and  aichotomous  and  have  two  rows  of  tubercles,  one  on  each 
umhilical  shoulder  and  a  row  on  either  side  of  the  keel.  It  is  also  to  be 
noted  that  the  venter  of  this  young  specimen  is  more  acute  and  the  whole 
fiirin  more  compressed  than  in  the  more  mature  stages. 

Localifi/:   France  and  Austria. 

Affe :  Senonian. 

Metatissotia  nodosa  n.  sp.  Hvatt. 

Tis»otia  haplophylla  (pars)  Ciros.souvre,   1893,  Ammonites  C'raie   superieure,  pi.   4, 
figs.  3,  4  (not  fig.  5). 

The  two  specimens  figured  by  Grossouvre  have  large  nodes  on  the 
umbilical  shoulders  like  those  of  haplophylla,  but  the  costfe  are  well 
developed  at  an  age  when  these  are  absent  in  true  haplophyUa,  as  shown  in 
Redtenbacher's  figure.  The  keel  at  the  same  stage  is  entire,  whereas  in 
haplophylla  there  is  a  row  of  tubercles. 

Locality :  France. 

Age :  Coniacian. 


48         FSEUDOCERATITES  OF  THE  CRETACEOUS. 

Metatissotia  HAPLOPiiYLLA  (Redtenbiiclier). 

A'linnonites  haj>J>>j>hi/ll(i  Redt('nl)acher,  1873,  Al)hancll.  K.-k.  o-col.  Reichsanstalt.  \ci\. 

V,  pi.  23. 
TisHotia  hajylopliijllii  (pars)  Grossouvre,  1893.  Ammonites  Craie  superieurc.  pi.   4. 

fig.  5  (not  figs.  3.  -4). 

This  form  is  ooiupressed,  lint  has  heavy  fold-like  costfe  and  very  stout 
nodes  on  the  umbilical  shoulder  and  ventro-lateral  angles,  the  venter  being- 
similar  to  that  oiM.fourneli,  but  with  a  line  of  nodes  instead  of  a  con- 
tinuous keel.  The  French  fossil  quoted  above  may  possibly  be  the  same, 
but  it  has  quite  a  distinct  aspect,  and  the  supposition  of  Grossouvre  that 
the  sutures  will  prove  to  be  similar  when  those  of  the  Austrian  specimen  are 
better  known,  is  not  sustained  by  the  collateral  evidence.  Grossouvre's 
figs.  3  and  4  of  the  supposed  neanic  stage  of  his  haplophylla  are  certainly 
quite  distinct,  having  an  entire  keel  and  aspect  allied  closely  to  Mefafissofia 
fourncli  and  rohini  and  here  treated  as  distinct  under  the  name  of  3feta. 
nodosa. 

Locality:  Austria. 

Age:  Senonian. 

Metatissotia  ewaldi  (von  Biich). 

Ainntonites  eimldi  \on  Bucli,  Abhandl.  K.  Akad.  Wiss.  zu  Berlin,  1848,  pi.  6,  figs.  •>.  7. 
Thsotia  eioaldi  (pars)  Grossouvre,  1893,  Ammonites  Craie  superieure.  pi.  -t,  fig.  6  (not 
pi.  9.  fig.  5). 

This  species  is  very  similar  to  Meta.  rohini,  but,  so  far  as  known  by 
the  figures  of  Grossouvre  and  others,  these  two  species  appear  to  be  distinct 
in  their  sutures.  Both  species  have  the  first  lateral  saddles  deeply  divided 
and  the  outer  arras  of  these  are  shorter  than  the  inner  ones,  but  the  outlines 
of  these  outer  arms  in  this  species  are  rounded,  phylliform,  undivided,  and 
straiglit  or  jiarallel  with  the  keel.  In  robini  these  outer  arms  are  inclined 
toward  the  keel  and  the  outlines  are  subdivided  by  marginal  lobes  in 
mature  specimens. 

Locality :   France. 

Aye:  Senonian. 


TISSOTIID.E.  49 

Mktatissotia  auressensis  (Peron). 

Timotia  auressenms  Peron,  1897,  Mem.  Soc.  geol.  France,  Paleontologie,  Vol.  VII, 
No.  17.  pi.  13.  figs.  4.  5. 

This  is  a  cast  of  what  is  apparently  an  old  shell.  The  form  is  not 
unlike  that  of  Paratissotia  grossouvrei,  with  a  similar  large  umbilicus,  and  it 
might  be  considered  as  perhaps  the  gerontic  stage  of  this  species,  but  the 
sutures  are  so  distinct  that  this  supposition  is  not  tenable.  These  have 
extraordinarily  large  and  long  phylliform  saddles,  and  the  first  lateral 
saddle  has  a  conspicuously  ti'ifid  base. 

Locality:  North  Africa. 

Age:  Senonian. 

Metatissotia  sLizEwifzi  (Fallot). 

Buchiceras  sUzewiczi  Fallot,  1885,  Ann.  sci.  geol..  Vol.  XVIII,  p.  240,  pi.  2,  tig.  2. 

Tissotia  sUzewiczi  Grossonvre,  1893,  Ammonites  Craie  superieure,  p.  Ifi.  fig.  2.5; 
pi.  7.  fig.  2. 

This  species,  if  correctly  given  by  Grossonvre,  has  a  young  form  which 
at  a  diameter  of  41  mm.  has  a  truncated  venter,  continuous  keel,  a  line  of 
small  tubercles  along  each  ventro-lateral  angle  beginning  on  the  last 
volution  at  about  this  size,  and  also  a  line  of  nodes  on  the  umbilical 
shoulders.  The  form  at  this  stage  is  like  that  of  Tissotia  c£  fourneli  Peron. 
The  sutures  are  also  similar  in  having  trifid  first  lateral  saddles  and  othei- 
saddles  and  lobes  long  and  large.  The  three  marginal  saddles  and  loljes 
are  much  more  completely  developed,  longer,  and  the  first  lateral  saddles 
broader  in  consequence  of  this  difterentiation  of  the  outlines.  The  nodes 
on  both  lines  are  much  larger  in  the  large  shell  figured  and  the  keel 
persists.  The  lunbilicus  is  also  of  good  size,  as  in  the  species  of  Peron 
referred  to  above.  Peron  considers  all  of  these  forms  to  have  occurred 
in  the  Senonian,  and  his  evidence  is  very  strong  on  this  point. 

Locality:  France. 

Age:  Coniacian,  base  of  Senonian. 

MON   XLIV— 03 1 


50  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

PARATISSOTIA  n.  gen.  Hyatt. 

Highly  compressed  smootli  fonn.s  like  the  type  of  this  genus,  P.  regularis 
eindficheuri,  omit  the  characteristic  nodose  stages  and  more  or  less  obtuse 
or  flattened  keeled  venters  of  Metatissrdla  or  else  pass  through  them  at  an 
early  stage,  becoming  later  highly  acute  and  smooth  or  at  least  without 
prominent  nodes  in  their  mature  stages.  In  the  two  species  examined 
thev  never  have  channeled  venters  at  any  stage.  The  discovery  of  a 
hollow  keel  in  the  later  stages  of  P.  regularis  would  have  caused  me  to 
separate  that  species  from  the  other  species  referred  to  this  group  had  their 
development  been  different  and  the  structure  of  their  keels  also  known. 

Paratissotia  gross(1uvrei  (Peron). 

Tmotia  ffrosscnivrei  Peron.  1S1>T,  Mem.  Soe.  geol.  France,  Paleontologie,  Vol.  VII, 
No.  17,  pi.  lt>.  tios.  1.  2. 

This  is  similar  in  a.spect  to  P.ficlieurl,  but  is  less  involute,  the  umbilicus 
beiiio'  much  larg-er  and  the  sutures  distinct.  The  first  lateral  saddles  have 
denticulated  outlines  instead  of  the  smooth,  phylliform  arms  of  P.  ficheuri 
The  voung  have  not  been  examined,  but  the  adult  appears  to  belong  to 
this  genus. 

Locality:  North  Africa. 

Age:   Lower  Senonian. 

Paratissotia  ?  THOMASi  (Perou). 

Tissotia  thomasl  Peron,  1897,  Mem.   Soc.  geol.   France,  Paleontologie,  Vol.  VII, 
No.  17,  pi.  13,  fig.  3  (not  pi.  16.  tig.s.  5.  6). 

The  type  of  this  form  is  a  compressed  shell  with  very  involute  whorls 
and  the  zone  around  the  umbilicus  depressed  and  flattened.  The  venter, 
at  least  in  advanced  age,  has  a  simple,  not  very  jjrominent  keel, 
unaccompanied  by  tubercles  of  any  kind  and  sides  almost  smooth. 

The  form  is  not  sufficiently  well  known  to  be  placed  here  without  a 
query  after  the  generic  name. 

Locality:  North  Africa. 

Aye:  Base  of  Senonian. 


TISSOTIID.E.  51 

Paratissotia  FicHEURi  (Cxrossouvre). 

Tif:sotiaiir}u'uri.  Grossouvre.  1S93,  Ammonite*  Craie  superieiire,  p.  35.  fig.  17. 
Tlssotia  fchcurl   Peron,  ISHT,  Mem.   Sue.   geol.    Fmnce,   Paleontologie,  Vol.  VII, 

No.  17,  pi.  12,  figs.  1,  2;  pi.  IS.  fig.  2. 
Bxichicm'os  eioaldl  (pars)  Peron,  1S90.  Moll.  Cret.  de  la  Tunisie.  pi.  1.5,  figs.  3-6. 
BacUcerm  fournell  (pars)  Bayle,  1S7S,  Expl.  de  la  Carte  geol.  France,  Vol.  IV,  pL 

40,  figs.  2  and  4  (not  fig.  3). 

This  is  a  very  mucli  compressed  shell,  with  no  chiinuels  on  either  side 
and  no  tubercles  on  the  costre,  which  are  simple  and  very  slightly 
developed.  The  keel  is  prominent  and  acute,  and  the  timbilicus  is  very 
small.  The  costre  are  shown  by  Peron  in  the  side  views  of  a  young 
specimen  having  a  diameter  of  55  mm.  and  in  a  very  old  shell  with 
diameter  exceeding  115  mm.  In  both  the  costa>  are  linear  and  straight, 
with  onlv  the  outer  half  developed.  A  description  of  this  last  specimen, 
which  is  evidently  very  old,  would  have  been  of  much  interest,  but  it  is 
not  o-iven.  The  very  broad,  low  denticulated  saddle  occupying  the 
extremity  of  the  ventral  lol)e  and  the  deeply  divided  denticulated  first 
lateral  saddles  of  this  species,  of  which  the  outer  one  is  bifid  and  the  inner 
has  a  broad,  phylliform  base,  are  very  peculiar,  as  are  also  the  costpe.  The 
very  globose  fossil  figured  on  pi.  15,  fig.  8,  by  Peron  in  his  Mollusques 
Cretaces  de  la  Tunisie  as  part  of  his  BucMceras  ewaldi  is  undoubtedly  a 
distinct  species,  but  the  information  given  is  too  limited  to  enable  one  to 
refer  it  to  any  known  sj^ecies.  The  reference  of  part  of  B.  fourneli  Bayle 
to  this  species  is  given  on  the  authority  of  Grossouvre.  Bayle's  figures 
are  handsome,  but  not  very  instructive. 

Locality:  North  Africa. 

Afje:  Base  of  Senonian. 

Paratissotia  serrata  (Hyatt). 

PI.  II,  figs.  7-11. 

BucMceras  serratum  (pars)  Hyatt,  1875,  Proc.  Boston  Soc.  Mat.  Hist.,  Vol.  XVII, 
p.  370. 

This  is  a  fragmentary  cast  of  more  than  one-half  of  an  entire  coil,  without 
livinfj-  chamber.  The  diameter  without  the  shell  is  37  mm.  The  outer 
volution  measures  20  ram.  at  larger  end,  the  umbilicus  4  mm.,  and  opposite 


52  PSELTDOCERATITES  OF  THE  CRETACEOUS. 

side  of  outer  volution  from  line  of  involution  to  venter  is  17  mm.  The 
shell  reduces  the  diameter  of  the  umbilicus  to  3  mm. 

The  cast  of  the  outer  volution  is  perfect  only  on  one  side.  This  is 
planoconvex  and  covered  with  regularly  arranged  costae,  of  which  there 
are  eight  to  half  of  a  volution  on  the  inner  part  of  the  whorl.  The  costae 
broaden  and  flatten  outwardly,  becoming  sigmoidal  in  curvature  and  then 
bifurcate,  the  branches  bending  well  forward  and  rising  into  elongated 
swellings  on  the  cast.  These  are  about  3  mm.  from  the  outer  edge  of  the 
keel,  and  tliere  are  very  slight  obsolescent  ridges  beyond  them,  which, 
however,  do  not  cross  the  smooth  bands  on  either  side  of  the  keel. 

The  venter  on  the  first  part  of  the  outer  volution,  the  third  quarter,  is 
subacute,  but  on  the  last  quarter  it  is  beginning  to  be  rounded,  the  keel 
having  disappeared.  This  shows  that  the  shell  was  in  the  gerontic  stage, 
and  the  approximation  of  the  last  two  sutures  also  indicates  the  same  stage. 
There  is  also  the  trace  of  a  line,  probably  a  line  of  involution,  impressed 
upon  this  part  of  the  outer  volution,  showing  that  the  living  chamber  must 
have  decreased  very  rapidly  in  the  amount  of  involution,  since  it  did  not 
cover  quite  half  of  the  sides  on  the  third  quarter  and  part  of  the  fourth 
quarter  of  the  now  exposed  volution.  The  length  of  the  absent  living 
chamber  could  not  be  determined,  but  that  it  was  much  rounded  and 
depressed  on  the  venter  and  in  an  extreme  stage  of  gerontic  degeneration 
is  highh"  probable.  Tiie  sutures  are  more  like  those  of  Faiatissotia fourneli, 
as  figured  by  Grossouvre  in  his  Ammonites  de  la  Craie  supe'rieure.  The 
ventral  lobe  is,  however,  very  short,  broad,  and  opens  widely,  with  two 
small,  short,  entire  arms.  The  siphonal  saddle  is  broad,  prominent,  and 
entire,  with  a  hardly  perceptible  median  marginal  lobe  or  depression,  which 
seems  inclined  to  disappear  in  the  gerontic  .stage.  The  first  lateral  saddle 
is  large,  as  in  other  species  of  this  group.  On  the  third  quarter  of  the 
exposed  volution  it  is  plainly  only  one  bifid  saddle,  but  on  the  fourth 
quarter  the  dividing  marginal  is  deeper,  and  there  appear  to  be  two  dis- 
tinct saddles,  as  in  P.  djelfensis.  The  outer  arm  of  the  saddle  shows  a 
hardly  jierceptible  median  marginal,  as  in  P.  fourneli.  Thei-e  are  five 
other  lateral  saddles,  all  entire,  and,  like  the  first  lateral,  very  short 
and  extremely  broad  like  those  of  P.  ficheuri,  as  figured  by  GrossouATe. 

The  first  lateral  lobe  is  broad  at  the  end  and  denticulated  exactly  as  in 
Tissotia  tissoti  and  Metafissotia  eivaldi  as  figured  by  Douville,  but  it  is  very 
short  and  broad.     The  second  laterals  are  smaller  and  also  denticulated. 


TTSSOTIID.E.  53 

The  remaining  lateral  lobes  are  like  those  of  the  same  species,  but 
very  much  narrower,  and  the  second  to  the  fifth  hardly  more  than  mere 
indentations. 

The  dorsal  sntnres  were  seen  only  from  above.  The  antisiphonal 
lobe  was  obviously  ver}-  narrow  at  the  base,  but  its  length  could  not  be 
determined.  There  are  seven  pairs  of  entire  zygous  dorsal  lobes  and 
saddles,  the  latter  nuich  narrower  than  the  external  laterals.  The  first  and 
second  lateral  saddles  are  connected  across  the  septum  by  broad  ridges,  so 
that  the  septum  observed  was  convex  externally  and  internally  along  the 
mesal  plane,  but  concave  along  the  center.  The  saddles  on  the  dorsum 
and  the  corresponding  extei'ual  saddles  were  connected  only  by  very 
slight  ridges,  and  the  intermediate  surface  of  the  septum  was  convex. 

The  figures  of  sections  show  the  liroad  globose,  keelless  form  of  the 
uepionic  stages  and  perhaps  of  the  earliest  of  the  neanic  stages.  The 
siphuncle  is  certainly  very  small  ;nid  the  keel  is  solid  when  it  first  appears, 
as  shown  in  figure.  The  disa|)pearance  of  the  siphuncle  left  me  in  doubt 
with  reference  to  its  structure  in  later  stages. 

LocaVdjj:  Cachiyacu,  west  side  of  Huallagua  River,  Peru. 

Age:  Upper  Cretaceous,  probably  Senonian. 

Paratissotia   regularis  n.  sp.  Hyatt. 
PI.  III.,  tio-s.  1-t!. 

Buchiceras  servatiun  Hyatt  (par.s),  l.s7,5,  Proc.  Boston  See.  Nat.  Hist.,  Vol.  XVII, 
p.  870. 

This  species  has  a  broad  volution  with  a  rounded  venter  until  tlie  shell 
reaches  a  diameter  of  G  nnn.  A  broad,  low  keel  next  makes  its  appearance 
and  the  next  volution  becomes  helmet-shaped  in  section.  There  is  cer- 
tainly one  line  of  nodes  on  the  umbilical  shoulders  at  this  time,  and  the 
umbilical  zone  is  broad  and  at  an  angle  of  about  45°  with  the  line  of 
involution.  This  helmet-shaped  section,  with  more  or  less  gibbous  sides, 
is  retained  through  life,  but  becomes  more  compressed;  the  keel  becomes 
subacute  and  prominent,  and  slight  concave  zones  apjjear  on  either  side  of 
it.  An  outer  line  of  tubercles  appears  on  the  edges  of  the  elevated  venter, 
and  both  lines  increase  steadily  in  size.  The  umbilical  zone  becomes 
rounded  and  is  in  the  first  ephebic  substage  at  right  angles  to  the  plane  of 
coiling.     The  two  lines  of  tubercles  are  connected  in  the  ephebic  stage. 


54         PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

aud  possibly  earlier,  by  faint  costse,  wliicli  bend  forward  ontu  the  venter 
but  do  not  cross  the  keel.  These  were  observed  on  the  ea.«t  alone,  no 
shell  being  present  on  the  parts  observed. 

The  young  were  seen  only  in  section,  and  the  nepionic  stage  was 
comjjletely  destroyed,  so  that  the  earliest  part  actually  seen  was  proliably 
in  the  ananeanic  stage.  The  sutures  were  developed  on  the  ephebic 
volution,  and  there  is  no  close  similarity  to  those  of  any  described  species 
of  this  genus.  They  have  a  siphonal  saddle,  and  first  lateral  saddles  on 
both  sides  more  like  those  of  Hemitissotia  djelfensis  Peron  than  any  other. 
The  inner  arm  of  this  saddle  is,  however,  bifurcated  instead  of  being  entire, 
and  the  outer  arm  is  trifurcate  instead  of  l^eing  bifurcate  as  in  that  species. 
The  siphonal  saddle  has  an  inner  rounded  marginal  like  that  so  common 
in  SpheitodiscKS.  There  are  five  pairs  of  entire  saddles  on  the  sides,  inside 
of  the  first  pair.  The  lobes  more  than  the  saddles  are  like  those  of  Peron's 
species,  liut  tliev  are  more  symmetrical  in  outline  and  longer  and  naiTOwer 
in  proportion.  It  is  interesting,  however,  to  note  that  its  nearest  affine  in  form 
is  also  an  African  species,  Paratissotia  ffrossouvrei  of  Peron.  This  is  close 
enough  in  external  aspect  to  have  been  considered  identical  but  for  the 
sutures,  which  are  quite  difterent.  Peron's  form  also  appears  to  have  had 
a  solid  keel.  The  surfaces  of  the  septa  and  the  dorsal  sutures  difi'er  from 
those  of  Paratissotia  serrafa  in  that  there  are  only  four  broad  zygous  saddles 
and  lolies  on  the  dorsum,  and  the  saddles  are  directly  connected  with  the 
external  saddles  by  broad  ridges  that  flex  the  floor  of  the  se])ta  correspond- 
ingly. The  internal  wings  of  the  septa  are  also  straight.  The  antisiphonal 
lobe,  so  far  as  seen,  seems  to  be  much  broader  than  in  that  species. 

The  voung  nmst  have  been  similar  to  that  of  Paratissotia  serrafa  in 
form,  and  keelless  until  the  neanic  stage  was  reached.  The  keel  was  at 
fii"st  solid  and  then  became  hollow. 

Locality:  Cachiyacu,  Peru. 

Age:  Upper  Cretaceous,  probably  Senonian. 

Incertae  sedis. 

TissoTiA  cossoNi  Peron. 
Tissotia  cnssovi  Peron,  1890,  Moll.  Cret.  de  la  Tuuisie,  pi.  16,  tig's.  1,  2. 

This  is  a  large  fossil,  248  mm.  in  diameter,  with  acute  venter  exactly 
similar  to  Sphenodiscus  in  aspect  and  evidently  extremely  aged,  as  shown  b}' 


TISSOTIID.E.  55 

the  ovei-lappiug  of  the  last  sutures.  These  have  h.\\%  liroad,  entire  saddles 
aud  broad  lobes,  very  different  from  any  observed  in  that  genus.  The 
youno-er  sutures  resemble  those  of  Tissofla  more  nearly  than  those  of 
Sphenodiscus,  the  saddles  being  phylliforni  and  entire.  The  ventral  lobes  as 
figured  are  quite  different  from  those  of  any  described  species,  so  far  as  I 
know.  How  )nuch  of  these  peculiarities  can  be  attributed  to  the  metamor- 
phoses of  age  remains  unknown,  but  these  ventral  lobes  have  apparently  no 
siphonal  saddles  except  a  minute  point  that  seems  to  be  becoming  obsolete. 
Unluckily  this  important  point  is  not  mentioned  in  the  description. 

Locality:   Bir  Oum-el-Djof 

Age:  Campanian. 

TissoTiA  GLOBOSA  u.  sp.  Hyatt. 

Thsotia  thammi  Peron  (pars),  1S9(»,  Moll.  Cret.  cU-  la  Tunisie.  pi.  Ifi,  figs.  5.  6  (not 
pi.  13,  fig.  3). 

This  fossil,  figured  on  pi.  16  Ijy  Peron,  has  a  globose  form  with  distinct 
proportions  from  the  type  of  tJiomasi,  and  the  umbilical  shoulders  are  quite 
prominent.     The  sutures  also  are  distinct  according  to  the  figure  given. 
The  aspect  indicates  affinity  with  Metatissotia  rather  than  Paratissotia. 
Locality:  North  Africa. 
Age:  Senonian. 

HETER0TI8S0TIA  Peron. 

If  the  type  of  this  genus  had  been  abraded  so  as  to  round  off  the  venter, 
its  sutures  wovild  have  placed  it  near  Tissotia,  if  not  in  the  same  genus. 
Nevertheless  the  flattened  venter  with  keel,  and  the  bifurcated,  fold-like 
costfe  ending  in  slight  tubercles  on  the  edges  of  the  smooth  ventral  zone  and 
gathered  into  a  few  large  nodes  on  the  prominent  umbilical  shoulders  are 
similar  to  those  of  several  species  usually  included  in  Pulchellia.  The 
affinities  of  this  fossil  appear  to  be  indeterminable  without  some  knowledge 
of  the  voung. 

Heterotissotia  neoceratites  Peron. 

Heterotis8otia    neoceratites   Peron,    ISttT,  Mem.    Soc.   geol.   France,  Paleontologie, 
Vol.  VII,  No.  17,  pi.  10,  figs.  9.  10. 

Sufficiently  described  above,  except  that  it  is  an  involute  compressed 
form  with  flat  lateral  zones  and  small  but  not  veiy  small  umbilicus.     The 


56         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

involution  covers  up  entirely  the  sides  of  the  last  volution,  but  it  is  obvious 
that  until  a  late  stage  preceding  this,  it  is  not  so  complete,  leaving  a  large 
and  more  open  umbilicus  in  the  young. 

Locality:  North  Africa. 

Age:   Senonian. 

SPHENODISCIDiE. 

This  is  a  provisional  group  to  include  genera  having  three  principal 
lateral  lobes  and  saddles  and  numerous  auxiliary  lobes  and  saddles  which 
are  more  distinctly  phvlliform  than  is  usual  in  the  Tissotidse,  also  having 
keeled  venters. 

There  are  three  genera:  Indoceras,  Libycoceras,  and  Sphenodisms.  The 
development  of  the  first  and  second  genera,  and  whether  they  have  a  solid 
keel,  is  not  known,  but  the  third  has  an  acute  venter  from  an  early  stage 
and  has  also  a  solid  keel.  Nearly  all  specimens  having  hollow  keels 
exhibit  a  truncated  aspect  on  the  venter  of  their  internal  casts  which  is 
not  shown  in  any  figures  of  Indoceras  and  Libycoceras 

INDOCERAS  Noetling. 

hidoceras  has  been  placed  in  the  Sphenodiscidfe  near  to  Libycoceras 
because  of  the  external  characteristics  of  the  later  stages  of  the  type  species 
described  below,  and  because  the  sutures  in  both  the  species  described  by 
Noetling  have  resemblances  to  those  of  Sphenodiscus.  As  in  many  other 
published  forms,  there  is  no  description  of  the  earlier  stages,  and  the  dorsal 
sutures,  whicli  would  also  greatly  assist  in  drawing  correct  inferences, 
are  still  unknown.  The  essential  distinction  between  this  and  Sphenodiscus 
lies  wholly  in  the  fact  that  the  saddles  are  entire  in  this  genus  instead  of 
being-  divided  or  denticulated  as  in  the  former. 

Indoceras  baluchistanense  Noetling. 

Indoceras  haluehistanejisis  Noetling,  1897.  Pal.  Indica,  Series  XVI,  Vol.  1,  pt.  3, 
pi.  21,  %.  2;  pi.  22.  tigs.  1-3. 

According  to  Noetling's  figures  and  descriptions,  this  interesting  species 
at  a  diameter  of  about  40  mm.  has  elongated  forward-bent  ridges  on  the 
outer  part  of  the  volution  that  are  obviously  the  remnants  of  sigmoidal 
costse.  The  venter  at  this  stage  is  somewhat  obtuse,  but  tending  toward 
being  subacute,  with  a  keel  bordered  by  smooth  zones  and  obscure  ridges 


SPHENOmSC'ID.E.  57 

on  either  side  In  later  stages  the  venter  becomes  planoconvex,  tlie  keel 
and  lateral  ridges  having  disappeared.  These  characteristics  are  very 
similar  to  those  of  Sjihenodiscus  pleurisepta.  The  sntures  have  entire  phylli- 
form  saddles  that  resemble  those  of  Sphenodiscus  more  than  those  of 
Tissotidfe.  The  first  lateral  saddles  are  described  by  Noetling  as  being 
bifid  in  this  species,  and  as  becoming  split  up  into  separate  saddles  during 
development.  There  appear  to  be  three  principal  lateral  saddles  in  the 
fullgrown. 

Locality:   Mazar  Drik. 

Age:   UpjDer  Senonian. 

Indoceras  aoutodorsatum  (Noetling). 

Sphenodiscus  acutodorsatuK  Noetling,  1897,  Piil.  Inclica,  Series  XVI,  Vol.  I.  pt.  3. 
pi.  21.  iig.  3. 

This  shell  has  the  usual  acute  volutions  of  Sphenodiscus,  but  the 
sutures  have  the  entire  saddles  of  Indoceras.  In  fact  the  onh'  distinction 
apj)ears  to  be  that  the  first  pair  of  saddles  ai'e  not  yet  completely  separated, 
but  appear  to  be  branches  of  a  first  lateral.  It  might  be  said,  therefore, 
that  this  species  had  only  two  principal  lateral  saddles,  the  first  and  second, 
the  first  being  deeply  bifid.  If  we  reckon  the  sutures  as  having  three  entire 
principal  lateral  saddles,  two  of  which  are  not  yet  fully  separated,  the 
species  passes  into  Indoceras. 

LIBYCOCERAS   Hyatt." 

This  genus  is  founded  upon  a  single  species,  which  has,  however,  sucli 
a '  peculiar  combination  of  characters  that  it  can  not  be  incorporated  with 
other  genera.  Zittel  recognizes  the  affinity  of  this  form  to  Sphenodiscus 
and  describes  it  as  liaving  three  principal  lateral  saddles.  The  sutures 
have  phylliform  entii'e  saddles  and  simply  digitated  lobes,  and  resemble 
those  of  the  young  of  S.  lenticularis  after  they  have  passed  through  the 
stage  in  whicli  both  saddles  and  lobes  are  entire.  The  median  lateral  line 
of  tubercles  and  l)road  costa*  connecting  these  with  an  outer  line  of  nodes 
along  the  edge  of  the  venter  and  distinct  keel  are,  however,  quite  different 
from  the  tubercles  and  eostse  and  solid  acute  venter  of  Sphenodiscus,  which 
has  distinct  sutures,  and  also  diff'erent  from  Indoceras,  which  has  similar 
sutures. 

aJifivKoi,  Libyan. 


58         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

LlBYCOCERAS    ISMAELE    (Zittel). 

Sp/ie)iodiscim  istnaeltK  Zittel.  Haiulb.  der  P;il;vontolot>-if.  Vol.  II.  p.  4.51.  fior.  fi.Sl. 
Lihycocerns  ismaeli  Hyatt,  1900,  Zittel's  Text-hook  of  Palaeontolofjy.  Vol.  I.  p.  .5><.''. 

According-  to  Zittel  this  has  three  principal  lobes  and  saddles. 
Localitij :   Libyan  Desert. 
Age:  Upper  Senonian. 

SPHEXODISCUS  Meek. 

This  genus  is  apparently  a  close  ally  of  Enffonoceras,  judging  Ijy  it> 
sutures  and  external  characters,  but  the  development  shows  it  to  be  verv 
distinct.  In  two  species,  pleurisepta  and  lentlcularis,  the  young  were 
examined,  and  in  these  there  were  no  indications  of  a  stage  having  a  flat  or 
concave  venter.  In  the  nepionic  stage  the  species  is  rounded  on  the  venter 
which  in  the  neanic  changes  directly  to  a  form  with  an  acute  venter  and 
flattened  side  like  that  of  the  adult.  There  are  three  principal  lateral 
saddles  derived  from  the  division  of  the  primitive  first  lateral  saddle. 

The  earlie.st  stage  described  in  S.  Jentlcularis  exhibits  sutures  like  those 
of  the  adult  of  Keolobites,  but  the}'  are  also  very  similar  to  those  of  some 
species  of  Engonoceras  having  longer,  narrower,  and  more  phvUiform  saddles 
than  usual,  like  Engonoceras  subjection.  There  is,  however,  in  Engonoceras 
and  in  Neolohites  also  a  very  distinct  persistent  first  lateral.  These  peculiar- 
ities in  development  of  the  sutures,  as  well  as  the  acute  venter,  heighten  the 
resemblances  to  the  shell  figured  by  Zittel  as  S.  ismaeUs.  This  is  genericallv 
distinct  and  here  described  as  Lihycoceras,  but  Sphenodiscus  might  be  a 
modified  form  of  the  same  series  in  which  the  keel  had  become  incorporated 
with  the  venter  and  with  more  comple.K  sutures,  whereas  its  development 
does  not  indicate  descent  from  an^"  of  the  genera  having  flat  and  tuberculated 
venters.  The  external  characters  of  this  g'enus  are  often  so  uniform  that 
the  sutures  as  a  rule  are  the  only  means  of  distinguishing  the  sj)ecies.  The 
exceptions  to  tliis  rule  are  to  be  found  in  the  American  forms  <S'.  jjleiirisepta, 
and  perhaps  acuttim,  and  the  European  representative  of  the  former,  S.  hinch- 
horsti,  which  have  lines  of  tubercles  and  faint  costae.  The  keel  is  solid,  and 
the  siphuncle  being  placed  well  within  the  sutiu'es  of  the  siphonal  saddles, 
is  protected  by  a  ridge  of  the  stony  filling  of  the  camera?  and  is  not,  there- 
fore, easih'  laid  bare  when  the  shell  is  remo\'ed  from  casts. 


SPHENODISCID.E.  59 

Sphenodxscus  pleurisepta  (Conrad). 
PI.  III.  tio-^.  7-15:  PI.  IV:  PI.  V.  tigs.  1-3:  PI.  VI.  tig.  6. 

Ammonites  2>l<'ui't>^<'l>tii  Conrad.  1S57.  U.  S.  and  Mex.  Bound.  Surv.,  Vol.  I.  Pt.  II, 

p.  159,  pi.  15,  tigs.  1.  a,  b,  c. 
Ammonites  pedemalis  Binckhorst,  1873,  Mon.  Gast.  et  Ceph.  du  Limbourg.  p.  'IX, 

PI.  V  a',  tig.  1  (no  others). 
Sphenodiscus  pleurisfptii  Bohm,  1898,  Zeitschr.  Deutsch.  geol.  (resell.  Vol.  L,  pi.  7. 

Conrad's  original  specimens,  preserved  in  the  United  States  National 
Musenin,  show  how  erroneous  and  misleading-  are  his  descriptions  and 
tioures.  The  orig-inal  of  his  fiscure  has  two  distinct  rows  of  lateral  tubercles. 
Another  specimen,  117  mm.  in  diameter,  is  the  one  cited  as  collected  by 
Schott,  "Yellow  Stone."  This  has  the  same  characteristics,  but  is  in  the 
gerontic  stage,  and  the  outer  row  of  tubercles  disappears  on  the  last 
quarter  of  the  outer  volution.  Tlie  condition  of  the  specimen,  however, 
made  this  somewhat  doubtful. 

A  number  of  fine  specimens  were  collected  by  Stanton  and  Vaughan 
near  Eagle  Pass,  Tex.  All  of  these  have  two  rows  df  nodes  on  the  sides, 
and  one  is  a  noble  specimen  182  mm.  in  diameter  (PI.  IV,  fig.  1-2).  What 
appears  to  be  the  abraded  edge  of  the  aperture  is  present  on  one  side,  and 
the  living  chamber  is  somewhat  over  one-half  of  a  volution  in  length.  The 
inner  row  tif  nudes  is  present,  but  the  outer  row  is  replaced  on  the  last 
volution  in  the  o-eroutic  staoe  \>\  broad  arcuate  folds.  These  are  visible 
throughout  the  volution  on  the  side  opposite  to  the  one  figured.  The 
venter  broadens  and  becomes  less  acute  on  the  third  quarter  of  the  ov;ter 
volution  and  is  rounded  on  the  last  quarter.  It  is  obvious  from  this  that 
the  specimens  described  below  were  in  some  cases  dwarfs,  the  range  being 
considerable. 

The  interesting  fact  in  this  large  specimen  is  that  the  lobes  and  saddles 
vary  but  slightly  from  those  of  smaller  fossils.  The  three  principal  saddles 
and  the  lobes  are  longer;  there  may  be  one  or  two  saddles  more,  making 
the  total  number  fourteen,  concealed  under  the  shell  of  the  umbilical  zone; 
and  the  marginals  are  more  numerous,  but  otherwise  the  sutures  are  just 
about  the  same  as  at  younger  stages.  There  are  only  five  divided  saddles, 
the  first  to  the  fifth,  as  in  younger  stages,  and  the  remainder  are  entire. 
Another  fact  is  that  the  amount  of  involution  decreases  so  slightlv,  even  in 


60         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

this  large  specimen,  that  it  is  hardly  perceptible.  There  is,  however,  a 
broader  umbilical  zone  in  the  paragerontic  substage  and  a  decided  umbilical 
shoulder. 

A  small  cast  of  this  species,  No.  19145b,  U.  S.  National  Museum 
(PI.  Ill,  fig.  14),  only  59  mm.  in  diameter,  shows  the  ephebic  stage.  The 
diameter  of  last  volution  from  line  of  involution  to  venter  on  cast  is  32  mm., 
the  same  diameter  on  opposite  part  of  volution  is  22  mm.,  the  umbilicus 
being  5  mm.  without  the  shell.  The  fragments  of  the  shell  are  not  specially 
thick  except  on  the  crest  of  the  venter,  where  it  forms  a  solid  keel,  and  in 
the  umbilicus,  where  it  is  over  a  millimeter  in  thickness. 

This  cast  is  somewhat  compressed,  but  judging  from  an  accompanying 
older  specimen  it  is  a  medium  stout  volution  with,  however,  a  ver}'  acute 
venter.  Tliere  are  two  lines  of  distinct,  transversely  elongated,  radiating 
nodes,  about  8  mm.  apart,  the  outer  line  occupying  the  centran  surface, 
about  7  mm.  from  the  venter.  The  inner  line  gradually  increases  its 
distance  from  the  umbilical  shoulder,  but  on  the  first  part  of  the  outer 
volution  begins  to  be  farther  removed  from  the  dorsum  than  the  (inter  row 
is  from  the  venter.  The  venter  is  blunted  on  the  last  part  of  the  exposed 
volution  and  the  parephebic  substage  had  ]n-obably  already  begun  in  this 
specimen. 

The  ventral  saddle  is  that  of  Sphenodiscus,  with  similar  marginal 
saddles  at  the  inner  corners,  but  the  aspect  of  the  lobes  and  saddles  is  like 
those  of  older  specimens,  except  tliat  they  are  shorter  and  the  sutures  do 
not  overlap  anywhere,  and  do  not  even  apjjroach  one  another  until  near 
the  umbilical  shoulders.  The  lobes  all  have  flaring  tops  and  the  saddles 
phylliform  and  rather  broad  bases,  flattening  out,  however,  as  usual  near 
the  uml)ilical  shoulders.  Nevertheless,  on  the  umbilical  zone  they  are 
again  slender  and  phylliform. 

The  first  lateral  saddles  are  trifid,  narrow  at  the  openings,  with  a  few 
phylliform  saddles;  the  second  and  third  are  bifid  a  trifle  longer,  but  of 
nearly  the  same  form;  the  third  beconu's  trifid  on  the  oldest  part  of  this 
volution;  the  fourth  is  trifid  and  then  becomes  quadrifid.  These  form  a 
bent  outline,  each  being  a  little  longer  than  its  neighbor,  beginning  with 
the  first  lateral.  The  fifth  is  bifid  and  from  thence  to  the  umbilicus  there 
is  the  usual  row  of  entire  saddles  gradually  shortening  up  and  sliowing 
more  and  more  primitive  forms;  but  they  become  narrower  again  tm  the 
uml>ilical  zone. 


SPHEN0D1SCID.E.  61 

The  branches  of  the  ventral  lobe  are  trifid  and  spreading  as  usual,  but 
small,  of  course,  in  such  a  suture;  the  first  laterals  are  shorter  and  broader 
and  together  with  the  longer  second  and  thii'd  laterals  form  the  usual  arch. 
The  fourth  lateral  is  about  half  the  length  of  the  third  and  from  this  to  the 
umbilicus  there  is  the  usual  diminishing  row.  The  type  is  bifid  except  the 
first  and  fourth  laterals;  these  were  uncertain.  All  are  divided  except, 
perhaps,  the  last  and  umbilical  lobes;  these  were  not  seen. 

There  are  twelve  saddles  and  twelve  lobes  visible,  and  there  may  be  a 
saddle  on  the  line  of  involution  on  the  left  side;  the  sutures  of  the  right 
side  were  not  seen. 

The  older  specimen  of  this  species  (PI.  Ill,  fig.  13)  is  a  cast  from  same 
locality  and  is  very  instructive.  It  is  90  nun.  in  diameter  and  the  form  is 
better  preserved,  not  having  been  injured  by  pressure.  The  oldest  part  is 
47  nun.  in  diameter,  the  umbilicus  without  the  shell  is  about  8  mm.,  and  the 
volution  opposite  is  Sf)  mm.  measuring  from  line  of  involution  to  venter. 
The  greatest  transverse  diameter  is  carried  farther  out  than  the  centran 
surface  at  this  age  and  is  21  mm.  between  the  tubercles,  the  greatest 
diameter  opposite  between  tubercles  and  about  centran  of  the  lateral  zones 
is  16  mm.     No  shell  is  present  in  anv  of  these  measurements. 

The  shell  is  excessively  thick  on  the  umbilical  zones  and  is  nearly  a 
millimeter  thick  on  the  sides  in  the  parephebic  .substage;  it  is  considerably 
thicker  on  the  venter,  where  it  forms  a  solid  keel.  There  are  two  lines  of 
tubercles  as  in  the  smaller  specimen,  the  age  of  the  first  part  of  this  volu- 
tion being  the  same  as  the  age  of  the  last  part  of  exposed  volution  in  the 
younger  specimen,  but  the  nodes  are  rounder  or  hardly  perceptibly  elon- 
gated. The  iimer  line  of  nodes  persists  and  retains  its  distance  from  the 
umljilicus,  but  the  nodes  are  slightly  nearer  to  the  venter  on  tlie  last  })art 
because  of  the  gerontic  decrease  in  the  rate  of  growth  of  the  dorsoventral 
diameter.  The  outer  tubercles  gradually  decrease  and  disappear,  but  the 
fold-like  short  costae  between  the  tubercles  persist.  These  costse  may  have 
a  bifurcated  aspect  when  slightly  better  developed  than  in  these  specimens. 
The  outer  part  of  the  whorl  is  decidedly  convex,  while  the  surface  between 
the  inner  line  and  the  umbilical  shoulder  is  decidedly  concave  and  the 
umbilical  zone  narrow  and  abrupt. 

The  earliest  part  of  this  volution  has  the  venter  bluntly  acute,  show- 
ing it  to  be  in  the  parephebic  substage,  while  on  the  second  quarter  the 
rounding  of  the  venter  and  loss  of  tubercles  shows  anagerontic  substage. 


62,         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Ou  the  tliird  quarter  folds  take  the  place  of  tubercles  of  outer  row,  and  on 
the  fourth  quarter  the  venter  becomes  gradually  rounded.  Thi.s  .shifts  the 
greatest  transverse  diameter  from  the  central  parts  of  the  sides  to  nearer 
the  venter.  There  is  also  a  very  slight  decrease  in  the  amount  of  involution 
internally. 

The  living-  chamber  is  only  in  part  preserved.  The  younger  sutures 
are  like  those  of  the  same  age  in  the  smaller  specimen,  but  are  a  tritle  more 
complex  in  outline  and  the  ventral  lobe  seemed  to  l)e  shorter.  This  last, 
however,  could  not  be  made  out  clearly  anywhere.  The  general  chai-acter 
of  the  sutures  is  the  same  as  in  the  younger  specimen,  so  far  as  all  of  the 
remaining  lobes  and  saddles  are  concerned,  and  there  are  five  divided 
saddles.  The  first  and  second  lateral  saddles  are  probably  bifid,  in  the 
young  becoming  trifid  later  and  perhaps  bifid  again  in  extreme  age."  The 
third  is  trifid,  becoming  quadrifid  later.  The  fourth  is  trifid  throughout. 
The  i-emainder  are  same  as  in  younger  specimen.  Lobes  appear  to  be 
about  the  same  as  in  that  specimen.  The  last  two  sutures  are  so  close 
together  that  they  overlap  more  or  less  throughout,  and  the  third  suture 
approaches  nearer  to  the  second  than  in  younger  parts  of  this  volution. 
This  specimen  had,  therefore,  in  all  its  characters  jjrobably  completed  its 
cycle  of  development  and  was  in  the  paragerontic  sitbstage.  There  are 
constantly  five  divided  saddles  on  l)otli  sides  of  specimens  of  this  species  so 
far  as  seen  hj  me. 

A  perfect  cast  (PI.  Ill,  figs.  7-12),  labeled  Rio  Pecos,''  in  collection  of 
Columbia  University,  is  60  mm.  in  diameter.  The  outer  volution  measures 
32  mm.,  transverse  diameter  is  13  nun.,  the  umbilicus  3.5  mm.,  the  opposite 
24.5  mm.,  and  the  transverse  diameter  between  tubercles  of  inner  row  9 
mm.  The  outer  volution  has  already  begun  to  show  a  blunted  or  rounded 
venter,  and  tlie  two  rows  of  elongated  nodes  are  more  distinct  than  in  other 
specimens  described.  These  also  begin  to  become  rounded  on  the  last  part 
of  the  outer  volution.  This  is  as  much  altered  in  the  form  of  the  volution 
(i.  e.,  venter  is  as  blunt)  at  this  size  as  a  second  specimen  from  same 
locality  (PI.  Ill,  fig.  1  (suture),  and  PL  V,  fig.  3)  at  diameter  of  86  mm 


"The  condition  of  the  sutures  of  the  paragerontic  stage  made  this  observation  somewhat  doubtful, 
because  when  slightly  worn  away  the  saddles  lose  their  secondary  divisions  and  become  bifid,  the 
central  marginal  lobe  being  always  more  persistent  on  account  of  its  greater  penetration  into  the 
interior  than  the  more  recently  acijuired  marginal  lobes  on  either  side  of  it. 

6  See  Mr.  Stanton's  note,  p.  6.5. 


SPHENODItiCID^E.  63 

The  first  specimen  is  the  only  one  with  perfect  young  that  I  have  seen, 
and  is,  therefore,  a  very  instructive  example  (PI.  Ill,  hg's.  9-12).  In 
ananepionic  stage  the  innermost  volution  next  to  the  large  protoconch  is 
rounded  and  followed  by  a  volution  still  in  the  nepionic  stage.  This 
acquires  an  elevated  venter  and  becomes  more  compressed  and  helmet 
shaped,  but  has  nowhere  a  flattened  or  concave  venter.  The  sutures  were 
simpler  than  those  of  later  age.  The  sutures  on  both  sides  had  five  divided 
saddles.  The  first  lateral  saddles  were  bifid  on  both  sides,  the  second  jiist 
besrinnino-  to  be  ciuadrifid,  the  third  and  fourth  symmetricallv  trifid,  and 
the  fifth  tinly  bifid  on  the  right:  whereas  on  the  left  side  the  second  to  the 
fifth,  like  the  first,  were  all  bifid.  The  volutions  in  section  were  similar  in 
outline  to  the  adult,  having  the  same  highly  involute  and  almost  pear- 
shaped  section  and  acute  venters.  Neither  of  these  specimens  showed  the 
living  chamber. 

One  specimen  (Loc.  582,  U.  S.  Geol.  Survey,  PI.  \,  figs.  1,  2),  when 
comjiared  with  more  typical  forms,  shows,  in  what  is  probably  the  mete- 
pliebic  substage,  the  outer  fold-like  costfe  as  in  the  gerontic  stage  of  others. 
The  diameter  of  the  cast,  without  the  shell,  is  about  lis  mm.,  partly  esti- 
mated. The  last  of  tlie  outer  volution  measures  60.5  mm.,  the  umbilicus. 
8  mm.,  and  the  opposite  volution  from  line  of  involution  to  venter  measures 
about  49.5  mm. 

The  acuteness  of  the  venter  decreases  on  last  part  of  this  volution, 
but  does  not  become  blunted  and  rounded  as  it  does  at  the  corresponding- 
size  in  the  typical  form. 

The  sutures  of  the  last  five  septa  show  gradual  approximation,  and  in 
the  closer  approach  of  the  last  two  there  are  indications  that  the  specimen 
was  beginning  its  gerontic  stage.  The  living  chamber  was  broken  away, 
but  the  marks  of  the  umbilical  parts  showed  that  this  had  extended  at  least 
one-fourth  of  a  volution  farther  on  the  sides.  The  inner  line  of  tubercles 
wa^  becoming  wider  apart,  and  together  with  the  venter  and  sutures,  also 
indicated  that  the  gerontic  stage  was  begun  or  was  about  to  begin,  and  had 
been  perhaps  nearly  completed  in  the  now  absent  living  chamber.  The 
sutures,  it  will  be  understood,  always  represent  a  later  stage  than  the  parts 
of  the  shell  on  the  inner  surface  of  which  they  are  found.  The  sutures 
have  short  phylliform  saddles  and  broad  lobes,  and  ai'e  well  separated  from 
each  other  and  approximate  only  near  the  umbilical  shoulders.     They  were 


64         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

more  perfect  on  the  side  opposite  to  the  one  figured.  The  first  lateral  sad- 
dles are  trifid,  the  second,  third,  fourth,  and  fifth  are  bifid  and  phylliform; 
the  remainder  are  similar  to  those  of  the  inner  columns  of  others  of  this 
species,  but  are  pei'haps  somewhat  simpler  in  outlines.  The  exact  number 
was  not  ascertained.  On  a  frag-ment  of  what  appeared  to  be  the  same 
species  from  the  same  locality,  tliere  were  thirteen  saddles  at  a  diameter  of 
60  mm.  from  line  of  involution  to  venter.  This  was  a  cast,  and  slightly 
abraded  on  the  venter.  The  ventral  saddles  were  much  worn  and  the  first 
lateral  saddles  were  entire,  except  for  a  faint  median  marginal  in  two 
sutures.  The  remaining  lobes  and  saddles  exactly  agreed  with  those  of 
the  ephebic  stage  of  the  first  specimen  described,  except  in  being  a  trifle 
longer.     There  were  five  divided  saddles,  as  in  other  specimens. 

One  of  the  figures  of  Amin.  pedernalis  given  by  Binckhorst  in  the 
monograph  quoted  above  was  taken  from  a  Texas  specimen  supposed  to 
be  identical  with  von  Buch's  species.  The  specimen  was  in  the  Museum  of 
Stuttgart,  and  was  said  to  have  come  from  Rio  Bravo  del  Norte,  Texas,  and 
to  have  been  collected  by  Schott.  This  figure  is  identical  with  the  larger 
vai'ieties  of  this  species  which  retain  the  acute  venter  until  a  late  stage 
of  development.  This  same  specimen  was  refigured  by  Bohm,  as  above 
quoted,  and  properly  named  by  him.  Except  in  being  somewhat  older 
and  large,  it  is  identical  with  the  fossil  figured  on  PI.  Ill,  fig.  15  (septum), 
and  PI.  V,  fig.  3.  The  first  lateral  saddles  are,  however,  bifid,  the  second 
trifid,  the  third  to  fifth  bifid,  whereas  all  the  saddles  in  sutures  on  PI.  Ill 
are  bifid,  and  this  holds  in  all  the  sutures  on  this  volution  in  this  fossil. 
Even  in  the  close  approximation  of  the  sutures  this  is  similar  to  Bdhm's 
figure  and  also  in  the  way  in  which  the  inner  line  of  nodes  trend  outward 
on  the  latter  part  of  the  volution. 

A  fragment  in  the  collection  of  Frederick  Braun,  of  Brooklpi,  N.  Y., 
is  labeled  as  from  rotten  limestone  grit,  Brooksville,  Noxubee  County,  Miss. 
The  diameter  of  side  is  55  mm.  The  inner  line  of  nodes  still  remains 
somewhat  elongated;  the  outer  line  is  superseded  by  broad  folds.  The 
fine  surface  of  this  cast  shows  that  the  shell  had  sigmoidal,  and  sometnnes 
dichotomous,  costse  and  ridges  on  the  outer  convex  half  of  the  volution, 
but  that  it  was  smooth  and  decidedly  concave  on  the  mner  half.  The  first 
lateral  saddles  were  trifid,  then  four  bifid  and  nine  entire.  There  were  ten 
entn-e  dorsal  saddles  at  the  same  age,  with  h^bes  like  those  of  the  exposed 


SPHENODISCID.E.  65 

sides.  Unluckily  the  antisiphonal  lobe  was  not  ex])(ised  by  excavation, 
and  therefore  it  was  not  considered  necessary  to  draw  these  curves.  Thi.s 
species  is  very  instructive,  since  its  external  characteristics  are  well  marked 
and  thev  show  that  the  amount  of  involution,  the  wneral  outlines  of  the 
lobes  and  saddles,  and  tlie  number  of  divided  saddles  remain  very  con- 
stant, while  the  trifid  or  bitid  outlines  of  the  larger  saddles  are  -variable. 
These  minor  details  of  the  saddles,  and  of  the  lobes  also,  depend  on  the 
relative  growth  of  marginals  and  ma}-  vary  at  different  stages  of  growth 
or  on  the  opposite  sides  in  some  individuals  or  in  different  individuals. 
The  numlxM'  of  sej^ta  may  also  greatly  vary,  thus  in  Bohm's  and  the  fossil 
figured  on  Pis.  Ill  and  Y  they  are  5  mm.  apait  near  the  center;  in  l^raun's 
they  are  9  mm.  distant  at  about  the  same  age  and  the  saddles  are  much 
longer. 

Another  specimen  from  the  same  collection  is  given  on  PI.  VI,  fig.  6, 
and  this  although  closel}'  associated  with  .S'.  lobatus,  and  apparently  at  first 
sight  the  }oung  of  that  species,  has  all  the  external  characters  and  the  sutures 
of  pleurisepta.  The  fossilization  is  in  the  peculiar  yellow  limestone,  with 
iron  incrustations  of  the  specimens  of  lobatus  from  the  same  locality.  It  is 
of  course  possible  that  this  specimen  may  be  the  young  of  lobatus,  which  I 
have  never  seen  of  as  small  size,  but  in  any  case  it  is  identical  with  jjkurisepta  of 
the  same  age,  which  has  an  acute  venter  on  the  outer  volution  and  sutures 
like  those  of  PI.  Ill,  fig.  15.  There  are  five  bifid  saddles  on  the  right  side 
at  the  point  where  that  side  is  about  30  mm.  broad,  aud  on  the  left  side, 
where  20  mm.  broad,  the  fifth  saddle  shows  the  faintest  possible  beginning 
of  a  median  marginal  division. 

Locality:  Near  Laredo,  Rio  Pecos,  and  near  Eagle  Pass,  Tex.;  Brooks- 
ville,  Noxubee  County,  Miss." 

Age:  Eagle  Pass  beds,  Upper  Cretaceous. 


"The  following  note  wa.«  contributed  by  Mr.  Stanton: 

"It  is  pretty  well  establij^lied  that  Conrad's  specimens  were  not  collected  near  Laredo.  It  is 
probable  that  they  came  from  the  neighborhood  of  Eagle  Pass,  where  the  species  is  abundant.  It  has 
been  collected  by  Geological  Survey  parties  from  localities  from  IJ  to  18J  miles  southeast  of  Eagle 
Pass. 

"I  doubt  whether  the  si^ecies  ha.s  been  found  on  tlie  Rio  Pecos.  There  are  certainly  no  beds  that 
could  have  yielded  it  near  the  mouth  of  that  stream." 

MON    XLIV — U3 5 


66  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Sphenodiscus  lobatus  (Tnoniev). 

PI.  VI,  lig-s.  1,  :i;  PI.  Vll,  figs  1.  2:  PI.  IX,  tig-s.  ll-i:^. 

Aiiimonites  lohaUi  Tuomey,  1856,  Proc.  Acad.  Nat.  Sci.  Philadelphia, Vol.  VII,  p.  ItiS. 

The  description  given  \i\  Tuomey  of  his  Amm.  lohatu  mav  of  conrse 
apply  to  another  species,  but  this  is  the  <>nly  one  I  liave  seen  to  which 
the  following  words  could  have  applied,  and  it  comes  from  the  same  State 
although  from  another  county:  "Shell  discoidal,  smooth,  thin  toward  the 
circumference;"  "dorsal  (ventral)  lobe  finely  serrate."  These  words  and 
his  reference  to  the  large  bilobed  saddles  as  characteristic  seems  to  make 
this  name  applicable  to  this  species,  which  is  so  widely  diflPerent  from 
Sphenodiscus  lenticularis  and  its  nearest  aflfines  that  no  discussion  is  necessary. 

A  fine  specimen  (PL  VI,  figs.  1,  2)  in  Coll.  Xat.  Museum,  labeled  S. 
lenticularis,  No.  20577,  from  Ripley  group,  Lander's  mill,  Tippah  County, 
Miss.,  is  111  mm.  in  diameter.  The  last  volution  at  what  appears  to  be  the 
aperture  measures  59  mm.  and  the  volution  immediately  opposite  in  same 
diameter  from  line  of  involution  to  venter  is  46  mm.  The  greatest  trans- 
verse diameter  is  about  the  middle  of  the  lateral  zone  and  is  21.5  mm.  and 
for  the  smaller  part  of  the  volution  15.5  mm.  The  cast  is  naked  except  a 
fragment  tliat  shows  that  it  did  not  have  a  very  thick  shell.  The  inner 
volutions  are  not  entirely  covered  and  the  umbilicus  is  larger  j)roportionally 
than  in  the  large  specimen,  supposed  to  be  the  adult  of  the  same  species, 
from  Pontotoc  County,  Miss.  There  are  obscure  fohl-like  costae  indicated 
outside  of  the  greatest  transverse  diameter,  which  is  nearly  central;  inter- 
nally the  surface  is  slightly  concave.  There  are  no  umbilical  shoulders 
and  no  flat  umbilical  zone  and  the  umbilical  openings  are  shallow.  The 
shell  nuist  have  been  very  thick  between  the  volutions  and  may  have  nutcli 
contracted  the  opening  of  the  umbilicus.  There  were  twelve  lobes  and 
thirteen  saddles  on  the  oldest  part  of  the  volution.  The  flat  siphonal 
saddle  has  a  minute  saddle  in  the  center  and  a  couple  of  inflections  or 
marg-inal  lobes  on  either  side  of  this  and  then  at  the  ends  two  small 
round  saddles.  The  ventral  lobe  is  very  broad  and  tlie  two  arms  also 
broad  and  obscurely  trilobate,  each  lobe  being  subdivided  l)y  a  minute 
saddle.  The  first,  second,  and  third  lobes  are  broad  at  top  and  have  an 
unequal  number  of  small  short  branches,  as  if  they  were  derived  from  the 
trifid  type.  The}'  are  all  probably,  however,  derived  from  a  bifid  type, 
unless  exception  may  be  made  for  the  branches  of  the  ventral  lobe. 


SPHENODISCID.E.  67 

The  remaining  lobes  have  one  large  median  saddle  and  an  ec^iial 
number  of  small  lobes  as  if  derived  from  tiie  bifid  type  There  is  a,  series 
from  a  primitive  bifid  lobe,  the  eleventh,  and  only  the  twelfth  lobe  is  single. 
On  the  right  side  the  twelfth  lobe  is  on  the  line  of  involution,  whereas  on 
the  left  side  that  line  is  occupied  by  a  saddle.  The  lobes  are  very  short 
and  broad. 

Tlie  first  six  saddles  have  broad  phvlliform  bases  and  the  first  five  are 
bifid  on  both  sides,  being  equally  divided  by  a  small  median  lohe,  the  sixth 
is  transitional  and  entire;  the  remaining  saddles  are  of  the  same  type  but  so 
short  and  broad  that  they  appear  to  be  flattened  at  the  base,  and  in  fact  are 
approximations  to  that  type. 

The  most  remarkable  fact  about  this  east  is  wliat  ai)pears  to  be  tlie 
living  chamber.  The  evidences  of  the  existence  of  a  perfect  living  chamber 
on  this  cast  seem  undeniable  and  there  is  every  mark  of  an  aperture  with  an 
entire  reflected  lip.  And  what  is  still  more  remarkable,  the  last  four  sutures 
on  the  left  side  are  shortened  as  if  absorbed  by  pressure  after  they  had 
been  built.  The  fourth  has  lost  the  three  inner  rows  of  lobes  and  saddles, 
the  third  has  lost  seven,  and  the  eighth  saddle  is  partly  gone;  the  second 
has  only  f(  )ur  saddles  left  and  faint  traces  of  fifth  lateral  lobe  and  outer  side 
of  the  saddle,  and  the  basal  septum  is  represented  by  hardly  perceptible 
traces  of  first,  second,  and  third  lateral  saddles,  no  ventral  or  imx  other 
lobes. 

On  the  right  side  the  pressure  of  the  bod}'  has  shortened  up  five  of  the 
sutures.  The  fifth  has  lost  all  the  inner  entire  saddles  and  their  lobes 
except  one-half  of  the  last  outer  one,  the  sixth  row  from  tlie  u}nbilicus  and 
the  seventh  from  tlie  venter.  Tlie  fourth  has  lost  this  remaining  half  and 
part  of  the  next  saddle,  the  thir<l  luis  not  been  absorbed  quite  so  far 
and  has  the  sixth  saddle  from  the  venter  and  part  of  the  next  inner  lobe, 
the  second  has  first  four  lobes  and  saddles,  but  only  one-half  of  the  suture 
of  the  fifth  saddle.  The  tracings  of  the  sutures  of  the  basal  septum  are 
slighter  than  on  the  other  side  and  includes  as  on  that  side  onl}'  the  faintest 
possible  traces  of  the  bases  of  the  first  tliree  saddles.  The  interval  between 
tlie  fifth  suture  on  tlie  right  side,  the  last  perfect  one,  and  the  apparent 
ajierture  on  the  line  of  involution  is  only  G  mm.  The  interval  between 
the  same  and  the  half  aljsorbed  sixth  saddle  (from  the  venter)  of  the 
second  suture  is  only  4  mm.     The  rostrum  of  the  aperture  is  incomplete, 


68         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

but  the  distance  from  the  last  ventral  siphonal  saddle  to  the  broken  edge 
is  22  mm."  The  almost  obsolescent  traces  of  sutures  of  the  basal  septum 
are  only  about  5  to  7  mm.  from  the  edge  of  the  aperture  on  the  sides,  and 
may  have  been  about  26-30  mm.  from  the  end  of  the  completed  rostrum 
on  the  venter. 

The  only  exjjlanation  that  I  am  able  to  suggest  is  that  the  animal  lost 
the  power  to  build  shell  after  it  had  constructed  this  aperture,  but  still 
continued  to  live  and  build  the  sutures  until  finally  the  pressui'e  of  the 
base  upon  the  last  sutures  put  a  stop  to  theii'  construction  near  tlie  lines 
of  involution,  but  allowed  it  to  go  on  with  decreasing  completeness  exter- 
nally. This  obliges  one  to  suppose  that  a  futile  attempt  was  made  to 
construct  the  outer  three  saddles  and  lobes  of  the  basal  septum,  and  that 
the  animal  slipped  back  upon  the  second  septum  after  failing  to  do  this. 
There  are  no  lines  connecting  the  broken  sutures  with  each  other  that  I 
could  detect.  The  reflected  i-im  of  the  cast  of  the  aperture  near  the 
umbilicus  in  some  nieasure  supports  the  opinion  that  the  animal,  failing 
in  having  a  proper  shell  wall  to  the  living  chamber,  spread  out  laterally 
and  the  reflected  extensions  of  the  aperture  were  built  by  the  lateral  parts 
of  the  body  wall  that  bulged  out  on  either  side.  In  that  case  the  animal 
miffht  have  had  an  abnormally  thin-shelled  living-  chamlier  which  was 
destroyed  after  its  death.  The  questions  that  such  suggestions  create  are 
far  more  difficult  tlian  I  can  answer  with  merely  a  single  cast  in  hand,  and 
an  entirely  satisfactorj"  solution  must  be  relegated  to  future  investigations. 

A  large  cast  (PI.  Vll,  figs.  1,  2;  PI.  IX,  fig.  13)  in  Coll.  Nat.  Museum,  No 
2403,  from  Pontotoc  County,  Miss.,  is  somewhat  over  265  mm.  in  diameter. 
The  diameter  of  outer  volution  from  line  of  involution  to  venter  at  the 
beginning  of  last  quarter  where  venter  was  complete  is  136  nun.;  same 
diameter  opposite  this  one-half  of  a  v<ilutiou, distant  is  92  nun.;  smallest 
diameter  79  nun.,  one-quarter  of  a  volution  younger  than  the  last. 

The  transverse  diameter  through  the  center  of  sides  corresponding  to 
first  diameter  is  57  nun.  and  for  second  39  mm.;  the  third  could  not  be 
measured.  The  right  side  is  a  little  worn  away,  so  that  these  transverse 
diameters  are  less  than  tliev  should  be. 


"These  suture.-*  are  not  like  the  imperl'eet  septa  ofcurrhig  in  Balhmocemx  and  some  Orthoeeratites, 
since  in  those  cases  the  animal  still  continueil  to  have  a  distinct  living  chamher.  They  are  in  some 
measure  similar  to  those  occurring  rarely  in  very  old  shells. 


SPHENODISCID.E.  69 

Tlie  form,  surface,  etc.,  are  the  same  as  in  smaller  specimen  above 
described.  The  sntures,  however,  being  much  more  mature,  are  quite  dis- 
tinct in  details  of  outline,  although  the  general  aspects  were  similar.  The 
saddles  have  the  swollen  jjhylliform  outlines  of  the  bases  and  the  lobes 
the  same  spreading  tops.  The  fii-st  and  second  lateral  saddles  on  the 
youngest  part  of  the  outei"  volution  are  trifid,  the  thiid,  fourtli,  and  fifth  are 
liiiid,  the  remainder  are  entire  and  i-ounded,  becoming  gradually  flattened 
and  more  depressed  toward  the  lines  of  involution.  This  was  on  the  side 
figured,  but  on  the  right  side  there  are  six  columns  of  divided  saddles,  the 
sixth  having  only,  however,  a  very  small  median  marginal.  The  first 
lateral  on  this  side  is  bifid,  the  second  trifid,  and  the  four  other  divided 
saddles  are  bifid.  The  first,  second,  and  third  lateral  lobes  present  irreo-u- 
larities  that  obscure  their  origin,  but  are  probably  from  the  trifid  type;  the 
remainder  are  all  distinctly  bifid.  There  are  about  fourteen  saddles  bevond 
the  fourth,  and  probably  two  rows  more  on  the  outer  part  of  same  volu- 
tion, since  the  spiral  arrangement  is  well  marked  and  the  sharp  umbilical 
sides  are  transformed  into  flat  zones  on  the  last  half  of  this  volution.  The 
saddles  and  lobes  are  more  complicated  and  the  first  more  deeplv  undercut 
near  the  end  of  this  volution,  but  there  is  no  other  marked  difference  pro- 
duced by  the  development  of  the  shell,  except  that  the  saddles  are  all  mark- 
edly longer  in  proportion  and  more  slender.  The  rotund,  phyllifoi'm 
aspect  of  the  bases  of  the  saddles  is  maintained  because  of  the  slow  devel- 
opment of  the  dividing  marginal  saddles.  The  sutures  are  easil)^  separable 
except  near  the  umbilicus.  The  ventral  is  a  trifle  longer  than  the  first 
lateral,  and  there  is  a  descent  from  the  last  to  the  third  lateral,  and  beyond 
this  a  decided  break  owing  to  the  sudden  decrease  in  the  fourth  lateral, 
which  is  only  one-half  the  length  of  the  third  lateral.  The  remaining  lobes 
and  saddles  slowly  decrease  in  length.  The  difi"erences  between  the  third 
and  fourth  laterals  decrease  in  the  older  parts  of  this  volution  and  the 
sutures  approximate  somewhat,  showing  the  approach  of  old  age.  The 
fragment  figured  by  Whitfield*  may  perhaps  be  a  specimen  of  this  species 
or  some  related  form.  Such  broad  internal  saddles  and  digitate  short  lobes 
occur  in  lohatus.  They  are  sirajiler  in  outline  although  belonging  to  a  larger 
specimen  than  that  here  described  as  variety  beecheri.  There  are  two  very 
large   specimens  in  American   Museum  of  Natural  History  in  New  York 

"Mod.  U.  S.  Geol.  Survey,  Vol.  XVIII,  pi.  41. 


70         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

City."  One  has  no  living-  cluunljer,  but  is  29(1  mm.  in  diameter.  Thi.s 
when  complete  must  have  been  nnich  larger  than  the  second,  which  is  over 
362  mm.  in  diameter.  The  living  chamber  was  jirobably  complete  and  was 
about  one-half  of  a  volution  in  length.  The  shell  existed  near  the  venter 
and  showed  a  completely  rounded  venter;  the  first  half  of  this  outer  volu- 
tion was  still  obtusely  subacute,  the  tendency  to  roundness  being  present 
only  on  the -last  half  Hardly  perceptible  broad  low  folds,  like  those  of 
smaller  specimens,  exist  on  the  sides  of  the  outer  volution  of  botli  these 
fossils.  The  sutures  are  more  com])lex  than  in  younger  specimens,  but 
still  have  about  the  same  elongated  phylliform  marginals.  There  is  also 
in  the  Academy  of  Natural  Sciences  in  Philadelphia  a  large  fragment  of 
this  species  having  smooth  sides,  but  the  specimen  was  not  in  hand  for  my 
final  revision.  The  concavo-convex  sides  of  the  ca.sts  of  this  species  and 
the  broad  outer  forward  curved  folds  are  similar  to  the  older  stages  of 
S.  pleurisepta,  but  no  tubercles  were  observed.  The  }oung,  so  tar  as  I 
know,  have  not  been  described. 

A  ver}'  interesting  variation  from  Buncombe  Hills,  Pontotoc  County, 
Miss.',  in  the  collection  of  Frederick  Braun,  of  Brooklyn,  N.  Y.,  is  shown  on 
PI.  IX,  fig.  11.  This  has  on  the  right  side  sutures  quite  ditfereiit  from  those 
of  other  specimens  figured.  The  diameter  is  about  155  mm.  and  the  breadth 
of  the  side  where  suture  is  shown  in  PI.  IX,  fig.  11,  is  about  8.5  mm.  The 
first  three  saddles  of  the  left  side  are  given  on  PL  IX,  fig.  12,  for  compar- 
ison with  those  on  the  left  side  of  lohatus  when  the  volution  was  about  the 
same  breadth.     There  were  five  divided  saddles  on  both  sides  of  this  fossil. 

Locality:   New  Jersey,  Mississippi. 

Age:  Ripley  group,  Upper  Cretaceous. 

Sphenodiscus  stantoni  n.  sp.  Hyatt. 
PI.  V.  %.  4;  PI.  VI,  tig  5. 

This  is  founded  upon  two  casts  from  locality  No.  1473  (Coll.  U.  S. 
Geological  Survey).  There  is  no  distinction,  so  far  as  could  be  seen,  to 
separate  this  from  S.  Icntiadaris  except  the  sutures.  These  have,  however, 
so  much  broader  and  shorter  saddles  than  any  specimen  of  that  sjiecies  I 
have  ever  seen,  that,  if  there  is  any  specific  distinction  in  such  peculiarities, 
these  forms  can  not  be  included  in  lenticularis.     The  same  })eculiarities,  as 


"Not  having  had  tliis  fus.sil  l)efore  nie  for  revision,  this  opinion  may  be  erroneous. 


SPHENODISCID^E.  7 1 

well  as  the  fact  that  the  sides  are  smooth  and  entirely  without  tubercles, 
also  separate  it  from  pleiirisepta. 

The  diameter  is  not  far  from  114  mm.  The  partly  preserved  living 
chamber  of  the  largest  cast  is  not  less  than  one-half  of  a  volution  in  length. 
About  midway  the  diameter  from  line  of  involution  to  venter  is  68  mm.,  that  of 
the  same  volution  opposite  this,  partly  estimated,  is  44  mm.,  the  umbilicus 
being  only  2  mm.  The  keel  was  solid  in  the  ephebic  stage.  The  basal  suture 
and  the  next  or  second  one  are  apparently  incomplete  on  the  right  side,  but  on 
the  left  they  are  both  present  but  depressed  toward  the  umbilical  shoulders. 
The  last  three  sutures  are  more  closely  approximated  than  others,  as  if  the 
shell  were  in  the  gerontic  stage. 

The  sutm-es  have  minute  marginal  lobes  on  the  saddles  and  lobes. 
The  first  lateral  saddles  are  very  short  and  broad  and  quadrifid,  the  mar- 
ginal saddles  are  small,  but  still  distinctly  subphylliform,  as  are  also  the 
second,  third,  and  fourth;  the  fifth  is  distinctly  phylliform  and  bifid,  the 
sixth  just  beginning  to  be  bifid  on  the  left  side,  while  on  the  right  side  it  is 
still  entire."  The  remaining  saddles  form  the  usual  series,  flattening  out  on 
the  bases  near  the  umbilicus.  On  account  of  the  short  saddles  the  sutures 
ai-^  as  widely  separated  on  the  venter  as  in  lobatus,  but  a  slight  overlapping 
beo-ins  at  the  third  veutrals  and  continues  to  the  umbilicus,  in  so  far  as  the 
sutures  were  seen  in  this  direction.  The  smaller  specimen  has  even  broader 
and  stouter  saddles,  but  the  umbilicus  is  not  so  much  contracted.  There 
were  five  divided  saddles  on  the  left  side  of  this  specimen  and  six  on  the 
right  side,  just  the  reverse  of  the  larger  fossil. 

Locality :   Eighteen  and  one-half  miles  southeast  of  Eagle  Pass,  Texas 

Age:  Eagle  Pass  beds.  Upper  Cretaceous. 

Sphenodiscus  lenticulakis  (Owen). 
PI.  VIII,  tig.s.  1,  2;  PI.  IX,  tig.s.  1-0. 

Ammonites  Ten tleul arts  Oweu,  1852,  Rept.  Geol.  Surv.  Wisconsin,  Iowa,  and  Minne- 

.sota,  p.  579,  pi.  8,  fig.  5. 
PlacenticeruH  lenticulare  Meek  (pars),  1876.  Men.  U.   S.  Geol.   Surv.  Territories, 

Vol.  IX.  fig.  66  on  p.  473  and  pi.  34. 

Meek's  original  specimen,  from  which  his  figures  were  taken,  shows 
that  these  are  accurate  with  exception  of  certain  minutiae.     Figure  on  page 

"The  sixth  column  of  saddles  was  entire  on  the  left  side  throughout;  on  the  right  it  was  just 
beginning  to  show  a  dividing  marginal,  the  diameter  of  the  side  along  this  line  being  about  53  mm. 


72  PSEUDOCEKATITES  OF  THE  CIRETACEOUS. 

473  of  the  work  cited  shows  acute  wings  to  the  siplnnial  saddle;  these  are 
pliylliforni  in  the  specimen,  as  is  usual  in  this  species.  The  marginal  lobes 
of  the  ventral  lol^e  are  too  pointed  in  this  figure.  The  auxiliary  saddles 
have  not  the  acute  corners  as  figured.  The  entire  saddle  in  fifth  column  of 
lowest  suture  is  a  mistake;  it  is  bifid  like  the  others  above.  The  siphonal 
saddle  is  not  perfectly  entire;  there  is  a  minute  marginal  depression  on 
either  side  of  the  center,  which  is  elongated,  forming  a  very  minute-pointed 
but  narrow  saddle  on  the  keel.  The  undiilicus  is  present  and  plugged  with 
dark  matrix,  and  the  shell  is  present  all  around  and  is  very  thick.  This 
was  entirely  overlooked  in  the  drawing.  The  figure  on  pi.  34  was  taken 
from  the  same  specimen  before  it  had  lost  the  very  friable  sliell  that  once 
covered  the  sides,  or  else  the  shell  was  in  large  part  restored.  In  this  figure 
the  lunbilicus  is  too  large,  llie  fold-like  costpe  as  figured  are  visible  only 
on  the  outer  half  of  the  outer  volution,  but  are  slightly  curved,  not  straight, 
and  are  more  decided  than  in  the  figure  The  inner  half  of  this  volution 
and  the  outer  part  are  smooth  zones  with  no  elevations  perceptible  to  the 
eve  or  touch. 

A  fine  young  one  of  this  species  (PI.  VIII,  figs.  1,  2)  (Coll.  National 
Museum,  Moreau  River,  South  Dakota),  has  the  living  chamber  only  partly 
preserved.  The  septa  and  sutures  are  straight  and  closely  approximated 
even  at  this  stage,  but  the  overlapping  in  consequence  of  this  is  more 
decided  near  the  umbilicus,  the  two  outer  saddles  and  first  lateral  lobes 
being  free  on  account  of  a  slight  bend  orad  in  this  part  and  the  greater 
space  at  the  peripher}^  According  to  Meek's  figure  the  inci-ease  in  size  and 
leno-th  of  these  saddles  in  the  later  stages  brings  them  into  contact.  The 
lobes  and  saddles  of  this  specimen  are  similar  to  the  style  of  Meek's  wood- 
cut on  page  473,  difiering  only  in  certain  details. 

There  are  six  columns  of  divided  saddles  on  the  left,  the  only  side 
visible;  the  first  and  second  are  just  passing  from  the  liifid  to  the  trifid  type, 
the  third  and  fourth  are  also  passing  from  the  bifid  to  tlie  quadrifid  type, 
the  fifth  is  bifid,  and  the  sixth  passes  on  the  first  and  second  quarters  of 
this  volution  from  an  entire  outline  into  a  bifid  condition.  The  five  inner 
columns  are  entire  and  the  fifth  column  is  seen  coming  in  on  this  volution. 
The  spiral  arrangement  of  these  inner  entire  saddles  is  prettily  shown  in 
the  umbilicus. 

The  lobes  all  belong  to  the  trifid  type  excei)t  tlie  three  inner  ones 
which  are  entire.     There  is  a  steady  series  of  gradations  in  complexity 


SPHENODISCID.E.  73 

beo-inuino-  with  the  fourth  coluiims  of  saddles  and  hibes,  both  becoming 
simpler  toward  the  umbilicus.  This  is  parallel  to  the  development  of  any 
row  taken  in  the  ontogeny,  as  explained  in  the  general  description.  There 
are  eleven  lobes  and  twelve  saddles,  besides  the  arm  of  the  ventral  lobe  on 
each  side  in  the  oldest  part  of  this  volution,  and  at  least  one,  perhaps  two, 
rows  of  lobes  and  one  row  of  saddles  less  on  the  very  earliest  part  of  this 
volution  when  the  shell  was  26  mm.  in  diameter,  and  from  venter  to  line  of 
involution  about  9  mm.  The  saddles,  when  a  little  older  than  the  suture 
figured,  had  the  phylliform  outlines  of  Meek's  figure  and  were  plainly  grow- 
ing to  be  more  like  his  figure  on  pi.  34.  Fold-hke  costse  about  1  mm. 
apart  occur,  but  these  are  elevated  above  the  general  surface  only  along  the 
median  surface  of  the  sides.  They  are  obsolete  outwardly,  and  inwardly 
they  are  mere  elevated  lines.  The  involution  almost  completely  covers  the 
volution  even  at  this  stage,  and  the  umbilical  opening  is  only  about  2  mm. 
in  diameter. 

The  venter  is  acute  on  the  youngest  part  of  this  volution,  ;ind  the 
shell  is  thin,  the  inner  coat  brilliantly  nacreous;  the  keel  is  solid.  This  is 
probablv  the  young  of  the  same  species  figured  by  Meek  on  pi.  34,  since 
some  of  the  first  lateral  saddles  already  show  the  tendency  to  attenuation 
and  the  i)hylliform  outlines  of  the  marginal  saddles  common  in  that  form. 
The  siphonal  saddle  also  has  the  same  form  as  in  that  species,  and  the 
dependent  marginal  saddles  on  either  side  have  the  peculiar  rounded  aspect 
of  the  same  parts  as  figured  by  him.  The  arms  of  the  ventral  lobe  are 
long  and  directed  laterally,  and  distinctly  trifid.  The  whole  diameter  is 
42  mm.,  diameter  at  last  septum  is  30.5  mm.,  broadest  volution  from  line 
of  involution  to  venter  19.5,  umbilicus  1.5  mm.,  and  smaller  part  of  same 
volution  opposite  9.5  mm. 

Fragments  of  one  or  two  specimens  of  the  same  species  (PI.  IX,  figs. 
1-6)  as  the  above,  from  Rock  Creek,  Wyoming  (Coll.  Yale  Museum, 
No.  1697),  show  similar  sutures  and  characters  The  age  and  size  of 
this  are  about  the  same  as  of  the  one  described  above.  There  are  seven 
narrow  phylliform  dorsal  saddles  in  the  zone  of  involution.  The  next 
to  the  youngest  fragment  of  a  volution  was  4.5  mm.  from  venter  to  line 
of  involution,  with  a  transverse  diameter  of  2  mm.  Even  at  this  early 
neanic  substao-e  the  form  of  the  venter  was  like  that  of  the  adult  and  tlie 
involution  almost  completely  concealed  the  next  inner  volution,  which 
was  paranepionic  and  quite  distinct  in  form.     The  diameter  of  the  youngest 


74         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

volution  is  al)out  1  mm.  from  venter  to  line  ot"  involution.  The  transverse 
section  is  stouter  than  in  second  voluiion,  the  outline  being-  helmet-shaped, 
and  the  venter  elevated  and  beginning-  to  be  subacute.  At  this  stage  there 
is  one  large  trifid  saddle  and  one  large  lateral  lobe,  and  the  large  inner 
.saddle  has  two  marginal  saddles  and  one  on  the  line  of  involution.  This 
enabled  nie  to  see  that  the  first  to  third  saddles  and  first  to  second 
lateral  lobes  of  succeeding  stages  were  made  by  division  of  the  first 
uepionic  saddles.  The  third  lobe  of  the  adult  consequently  represents 
the  primitive  lateral  uepionic  lobe,  and  the  remainder  of  the  saddles 
and  lobes  were  derived  from  the  division  of  the  outlines  of  the  inagno- 
sellarian  or  second  lateral  uepionic  saddles.  In  the  zone  of  involution 
there  is  a  deep  antisiphonal  lobe  and  a  pair  of  large  saddles  with  a  pair 
of  broad  lobes  and  small  saddles  at  the  lines  of  involution  The  .specimen 
has  tlie  color  and  transparency  of  amber  and  the  enlarged  drawing 
(PI.  IX,  fig.  2)  represents  what  was  seen.  There  was  a  decidedly  swollen 
joint  at  each  septum  of  the  three  seen.  A  collar  was  dimly  seen,  and 
there  appeared  to  be  but  one  long  funnel  reaching  across  the  chamber. 
This  seemed  to  be  the  fact,  and  yet  I  do  not  think  it  was  clear  enough  to 
be  considered  certain.  Such  a  long  funnel  would  be  a  remarkable  case  of 
arrested  development,  especially  when  a  collar  was  present.  It  may  he 
that  the  appearances  were  due  to  the  entire  absence  of  any  true  funnel. 
This  last  view  would  entirely  reverse  the  statement  and  show  a  high 
degree  of  acceleration,  since  the  disappearance  of  the  funnel  usually  takes 
place  later  in  life  in  most  Jurassic  and  Cretaceous  forms.  In  the  neanic 
substage,  perhaps  in  the  ananeauic,  above  mentioned,  the  first  three  saddles 
still  show  the  curvature  of  the  great  first  lateral  uepionic  saddle.  The 
ventral  lobe  is  broad,  as  in  the  adult.  The  siphonal  saddle  is  prominent 
and  broad,  but  as  yet  shows  no  digitation,  only  a  few  faint  indentations. 
The  arms  of  the  lobe  are  just  passing  from  the  entire  hastate  to  the  trifid 
type.  The  first  two  lateral  lobes  are  in  the  same  condition,  but  the  saddle 
remains  entire  and  club-shaped.  In  fact,  at  the  stage  immeiliately  pre- 
ceding this,  the  three  principal  derivative  saddles  and  lobes  must  have  been 
almost  exact  rejietitions  of  those  of  Prolecanites  among  Goniatitina-.  The 
fourth  saddles  are  entire,  but  rather  short,  and  beyond  are  three  saddles  still 
verv  primitive  in  outline.  The  dorsal  has  an  entire  antisiphonal,  more 
club-shaped  than  in  the   vounger  stage,  and  there  are  four  other  pairs  of 


SPHENODISCID.E.  75 

zygous  entire  saddles  niid  three  pairs  of  similar  lobes.  The  globular  first 
stage  had  been  lost  out  of  this  frag-ment  before  it  came  into  my  hands.  The 
sutures  have  five  columns  of  bifid  saddles  on  the  right  side  and  six  on  the 
left  side  when  the  volution  is  about  10  nun.  broad.  The  suture  figured 
was  taken  from  a  volution  about  12  mm.  broad  transversely  (Pl.  IX,  fig-  5). 
The  dorsal  sutures  are  of  the  same  age,  but  were  drawn  on  a  larger  scale 
bv  mistake  and  have  been  separated  as  a  distinct  figure  on  that  account. 

There  is  an  interesting  small  specimen  in  the  Academy  of  Natural 
Sciences,  Philadelphia,  said  to  be  from  near  Santa  Fe,  N.  Mex.  In  this 
museum  and  in  the  United  States  National  Museum  there  are  fragments  of 
volutions  of  large  size  having  very  broad,  coarse,  low  folds  on  the  outer 
half  of  the  sides;  these  may  belong  to  this  species.  The  largest  is  102  mm- 
from  line  of  involution,  which  was  not  wholly  complete.  The  sides  are 
rather  gibbous,  the  venter  still  subacute,  although  not  so  sharp  as  in  earlier 
stages.  Tlu-ough  the  thickest  part  about  34  mm.  from  keel  the  transverse 
diameter  is  51  mm  The  absence  of  tubercles  at  all  ages  was  completely 
demonstrated  in  this  species.  The  concave  zone  found  along  the  inner  half 
of  the  older  volutions  in  S.  pleurisejita  and  lohatus  was  not  present  in  this 
species,  although  low,  fold-like,  arcuate  costs  were  found  as  figured  by 
Meek  in  older  stages  on  the  outer  parts  of  the  whorls. 

Locality:  ^Moreau  River,  South  Dakota;  Rock  Creek,  Wyoming;  Santa 
Fe,  N.  Mex. 

Age:   Fox  Hills  group,  Upper  Cretaceous. 

Sphenodiscus  lenticulakis  variet}'  splendens  Hyatt. 

PI.  Vm,  tigs.  3-7. 

A  young  fragment  broken  out  of  an  older  volution  is  in  the  form  of 
a  cast,  but  with  the  sutures  and  septal  partings  beautifully  marked.  It 
has  the  usual  ax-like  venter  of  its  congeneric  forms,  with  fold-like,  arcuate, 
very  obscure  costse  showing  on  the  outer  parts  of  the  sides.  The  extreme 
acuteness  of  the  venter  shows  that  this  species  had  a  solid  keel.  The  first 
to  the  sixth  saddles  on  the  right  side  and  the  first  to  the  fifth  on  the  left 
side  in  the  smaller  cast  and  also  in  the  larger  are  bifid.  An  observer 
seeing  the  young  on  one  side  and  the  older  fragment  on  the  other  would 
be  apt  to  consider  this  lateral  difference  as  a  distinction  due  to  age.     The 


76         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

basal  parts  ot"  the  saddles  have  marginal  lobes  like  those  of  lohatus,  but 
these  are  longer  and  divide  ^x\)  the  body  of  the  saddle  more  completely, 
making-  a  more  complicated  outline,  with  long,  phylliform,  marginal  saddles 
on  the  first  three  saddles.  The  lobes  and  saddles  of  the  inner  part  are 
very  closely  similar  to  the  older  ones  of  the  typical  specimens  described 
above,  having  similar  phvUiform  Ijranches  and  deeply  cut  outlines.     . 

At  a  diameter  from  line  of  involution  to  venter  of  43  mm.  in  the  younger 
fragment  the  sutures  are  closely  approximate,  the  outlines  overlap  slightly 
on  the  third,  fourth,  and  fifth  columns  and  then  separate  toward  the  centran 
surface,  but  remain  close  and  become  overlapped  again  near  the  umbilicus. 
The  lobes  and  saddles  are  comparatively  long  and  with  highly  complex 
outlines  even  at  this  stage,  and  the  phylliform  marginal  saddles  remind  one 
strongly  of  Fhylloceras.  These  are  shorter  and  stouter  than  the  same  parts 
in  the  older  stage,  but  even  at  this  stage  the  first  lateral  saddles  are  more 
comidex  than  the  sutures  of  var.  mac/nificus  and  tlie  whole  aspect  is  more 
phylliform.  The  first  lateral  saddles  are  trifid,  l)ut  obviously  modified  from 
the  bifid  type;  the  second,  third,  and  fourth  are  quadrifid,  modified 
from  the  bifid  type;  the  fifth  is  bifid;  the  sixth  is  beginning  to  show  the  bifid 
division  on  the  right  side,  but  on  the  left  is  entire.  There  are  twelve  sad- 
dles in  all,  but  the  remainder  are  entire  and  tend  as  usual  to  become  shorter 
and  flatter.  The  ventral  saddle  is  similar  to  that  of  var.  mugnificus  and 
S.  hbatiis,  with  large,  rounded,  marginal  saddles  at  the  corners.  The  ven- 
tral lobe  is  broad  with  broad  and  short  branches,  belonging  to  the  trifid 
type.  The  remaining  lobes  are  complicated  with  marginal  branches,  but 
are  of  the  bifid  type,  although  this  is  not  so  noticeable  in  the  first  five  lobes 
as  in  the  smaller  and  less  complex  ones  of  the  sixth  to  the  twelfth  column. 
There  may  have  been  one  more  pair  of  lobes  inside  of  these  which  were 
broken  away. 

From  line  of  involution  to  venter  the  large  fragment  had  a  diameter  of 
103  mm.  with  the  same  surface  features  as  on  the  smaller  cast,  but  with  the 
venter  not  so  acute.  The  sutures  are  older  and  more  complex,  as  noted 
above,  and  there  were  the  same  dift'erences  between  the  two  sides. 

There  are  twelve  lobes  and  thirteen  saddles,  and  there  was  certainh'  one 
row  of  lobes  broken  away  and  probably  another  of  saddles  gone  from  the 
undiilical  edg-e.  The  inner  three  saddles  are  considerabh"  flattened;  the 
next  four  rows  are  rotund,  as  in  the  younger  stage  described  above;  and 


SPHENODISCID.E.  77 

the  other  rows  to  the  venter  have  the  elongated  aspect  of  the  ephebic 
sutures  of  this  variety.  The  outer  or  first  laterals  are  slightly  more  distant 
from  the  lobes  than  in  the  ephebic  substage,  but  the  second,  third,  fourth, 
fifth,  and  sixth  laterals  overlap  the  lobes  more  than  in  that  stage.  The  con- 
tour of  the  venter  and  aspect  of  the  sutures  do  not  indicate  advanced  age. 
The  largest  fragment  was  probabl}^  only  in  the  parephebic  or  anagerontic 
substage  and  must  have  belonged  to  a  much  larger  sliell. 

Mr.  Stanton  has  kindly  sent  me  a  tracing  of  a  suture  from  a  large 
specimen  which  he  supjioses  is  the  one  that  furnislied  the  suture  figured 
by  Meek  on  pi  34..  This  suture  has  attenuated  saddles  and  lol^es  more 
like  those  of  var.  splendtns  than  the  typical  lentlciilarls. 

LocuVdij :   South  Dakota. 

Age  :   Fox  Hills  group,  Upper  Cretaceous. 

Sphenodiscus  lenticularis  variety  mississippiensis  Hyatt. 

PI.  IX,  lig-s.  7-9. 

There  are  two  more  or  less  crushed  specimens  in  the  National  Museum 
from  friable  marls  on  C)wl  Creek,  3  miles  northeast  of  Ripley,  Miss., 
No  20863.  Tliese  have  smooth  shells,  except  for  well-defined  bands  of 
arrowth,  and  evenly  convex  sides  and  sutures  that  are  more  like  those 
of  lentkularis  than  those  of  any  other  species.  Tlie  lobes  and  saddles  are 
lemarkably  long  and  similar,  and  although  the  ventral  saddles  are  difi'erent, 
they  are  not  widely  difterent.  The  largest  fragment,  belonging  to  a  fossil 
probably  about  200  ram.  in  diameter,  has  only  five  colunms  of  divided 
saddles  on  the  riglit  side  (PI.  IX,  figs.  7,  8).  The  actual  breadth  of  the  side 
where  this  suture  was  studied  is  111  mm.  The  dorsal  saddles  are  remark- 
ably unsymmetrical,  and  these  and  the  antisiphonal  lobes  are  difterent 
from  those  of  the  western  variety  splendens,  and  further  investigations 
may  show  these  to  be  distinct,  but  the  materials  do  not  seem  at  present 
to  justify  a  separation  The  suture  of  the  smaller  specimen  (PI.  IX,  fig.  9), 
taken  where  the  side  was  about  78  nun.  broad,  agrees,  considering  the 
difi'erence  of  age,  nearly  enoiigh  with  that  of  the  preceding  to  be  placed 
in  the  same  variety,  but  the  dorsals  were  not  seen.  This  cast  is  identical 
with  that  shell  in  extern^Tl  aspect  and  has  the  shell  partly  ]n-eserved  on  one 
side.     This  has  the  usual  brilliantly  nacreous  layers,  and  what  seems  to  be 


78         PSEUDOCERATITES  OF  THE  CRETACEOUS 

the  external  layer  is  also  nacreous.  The  growth  ridges  certainly  give  the 
aspect  of  an  external  shell,  l»ut  this  may  be  due  to  the  fact  that  the  secimd 
or  middle  layer  takes  the  lines  as  impressions  from  the  outer  la^■er,  which 
is  absent  in  this  and  in  tlie  larger  fossil  also.  This  last  has  a  very  distinct 
noimacreous  or  only  faintly  nacreous  inner  layer;  the  middle  layer  is 
l)rilliantly  nacreous,  as  usual,  but  the  lines  of  growth,  although  present,  are 
not  so  well  marked  as  in  the  smaller  specimen.  In  both  specimens  these 
lines  indicate  a  well-marked  rostrum  with  broad  lateral  sinuses,  median 
lateral,  broad  crests — similar  broad  sinuses  internally  rising  toward  the 
umbilical  shoulders.  The  diameter  was  jiartly  estimated  at  lo?  imn. ;  the 
diameter  of  living  chamber,  which  is  nearly  complete  and  one- half  of  a 
volution  in  length,  is  about  90  mm.  at  aperture. 

A  cast  from  South  Carolina  (Coll.  American  Museum  of  Natural 
History,  New  York),  is  151  mm.  in  diameter.  The  living  chamber  is  a 
trifle  over  one-half  of  a  volution  in  length  where  complete  on  the  umbilical 
shoulder.  The  form  and  other  characters  are  like  those  of  lenticularis  and 
the  saddles  have  exactly  the  attenuated  outlines  given  in  Meek's  pi.  34,  Init 
are  much  shorter,  and  are  also  quite  distinct  from  those  of  Meek's  other 
figures  of  this  species.  The  auxiliary  saddles  have  the  peculiar  phylliform 
bases  given  in  that  figure.  The  inner  edge  of  aperture  is  pr(;sent  on  one 
side  and  shows  that  internally  the  living  chamber  was  about  one-half  of  a 
volution  in  length.  The  venter  was  solid.  Steinmann,  in  his  Elemente 
der  Palaeontologie,  Vol.  II,  p.  415,  figm-es  a  specimen  said  to  be  from 
upper  Missouri,  with  the  typical  suture  line  of  this  species,  but  having  a 
line  of  median  lateral  nodes.  He  gives  four  derivative  lateral  saddles,  but 
there  are,  in  my  opinion,  only  three,  the  remainder  belonging  to  the 
auxiliary  system.  The  nodes  may  be  the  inner  termini  of  the  costae, 
perhaps  slightly  more  prominent  than  usual.  True  nodes  are  not  present 
in  any  specimen  I  have  seen. 

Sphenodiscus  beecheri  n.  sp.  Hyatt. 

PI.  VI,  tigs.  3,  4;  PL  IX,  fig.  10. 

The  type  of  this  species  is  a  large  specimen  in  Collection  of  the  Museum 
of  Comparative  Zoology,  labeled  "Central  City,  Colorado,""  but  the  real 


"Mr.  Stanton  has  most  kindly  correcti'il  this  as  follows:  "This  locality  is  an  error.     Central  City 
is  in  the  midst  of  a  granitii;  region  and  30  or  40  miles  from  the  nearest  Cretaceous  outcrops." 


SPHENODISCID.E.  79 

locality  is  probably  Fox  Hills,  Dakota.  It  is  2(i3  min.  in  diameter  without 
the  shell,  which  was  not  present  on  the  venter.  The  shell  would  have 
increased  the  measurement  to  about  267.5  mm.,  judging  by  the  shell 
preserved  on  the  venter  of  the  next  inner  volution. 

The  living  chamber  is  complete  and  about  one-halt'  of  a  volution  in 
length,  and  the  diameter,  from  line  of  involution  to  venter,  is  150  mm. 
The  outlines  of  the  aperture  are  sufficiently  well  preserved  to  show  that  it 
has  in  this  old  stage  very  low,  broad  crests  on  the  sides,  slight  sinuses 
between  these  and  the  rostrum;  tliis  last  being  also  obtuse  and  not  much 
extended,  the  outlines  l)eing  the  same  as  the  lines  of  growth  described 
elsewhere.  Even  at  this  large  size  the  venter  is  still  acute.  The  inner 
volution  is  covered  and  the  umbilicus  is  only  about  1.5  mm.  It  is  as  near 
as  possible  to  being  completely  closed  by  the  thick  sliell,  althougli  in  casts 
it  is  obviously  much  wider  open.  The  shell  is  about  3  nun.  in  thickness 
near  the  lines  of  involution.  It  is  also  quite  thick  over  the  entire  last 
volution,  whenever  present,  and  consists  of  the  usual  outer  opaque,  middle 
iridescent,  and  inner  pearly  layers.  The  keel  was  solid,  so  far  as  seen,  at 
all  stages. 

There  are  fold-like  obscure  costpe,  very  broad  on  the  oldest  part  and 
visible  only  on  the  outer  part  of  the  volution,  as  in  the  casts  of  *S'.  Jenticularis 
var.  splendens.  The  venter  has  the  same  form  ;is  in  the  young,  namely,  an 
ax-like  solid  edge  with  biconvex  sides  to  the  edge,  forming  obscure  smootli 
zones  on  either  side.  There  are  no  tubercles  on  any  parts  visible,  but  the 
bands  of  growth,  as  in  other  species,  are  very  well  marked  on  the  outer 
shell.  The  sutures  (PI.  IX,  fig.  10)  have  broader  saddles  than  th(<se  of 
Meek's  figure  on  })1.  34,  but  thev  are  quite  similar  to  those  of  <S'.  lenficu- 
laris  vai'ietv  splendens,  except  that  they  are  more  complex  and  have  a  larger 
number  of  divided  saddles. 

The  branches  of  the  ventral  lobe  are  similar  to  those  of  S.  Icj/ticularis, 
but  longer  and  narrower.  The  first  lateral  is  much  shorter  than  the 
ventral  branch  and  the  second  lateral  lobe,  and  the  second  lateral  is  shorter 
than  the  third  lateral,  so  that  this  part  of  the  suture  is  decidedlv  convex 
and  has  not  the  fiat  aspect  of  the  same  part  in  Meek's  figure.  The  lobes 
are  also  of  the  trifid  type,  a  difference  not  accounted  for  by  the  difference 
of  age,  as  is  the  fact  also  that  they  are  more  complicated  in  outline.  The 
fourth  to  the  eighth  are  quadrifid,  as  are  the  second,  third,  and  fourth  in 


80         PSECDOCERATITES  OF  THE  CRETACEOUS. 

Meek's  iigv;re  and  also  sixth,  seventh,  eighth,  and  nintli,  wliik-  tlie  fourth 
and  fifth  are  triiid.  The  ninth  lobe  is  of  the  ])rimitive  trifid  type;  those 
interior  to  this  were  not  seen.  The  first  lateral  saddle  is  unsynnnetricalh' 
trifid,  the  second  to  tlie  fdurtli  more  symmetrical  but  rather  irregularh- 
quadrifid,  the  fifth  and  sixth  trifid,  the  seventh,  eighth,  and  ninth  bifid, 
with  broad  phylliform  bases,  the  tenth  entire.  The  remainder,  ])robabh' 
at  least  two  more,  were  not  seen. 

The  lines  of  the  sutures  are  ([uite  distinct  and  are  separated  by  a 
considerable  interval  to  the  third  lateral  saddle  in  the  older  septa,  and  in 
the  younger  septa  this  separation  is  maintained  until  the  innermost  lines 
of  bifurcated  saddles  are  reached. 

A  fragment  from  Fox  Hills,  collection  Museum  CJomparative  Zoology, 
No.  397,  shows  that  this  species  must  have  attained  a  much  larger  size  than 
the  specimen  described  above.  The  sutures  are  visible  on  this  fossil,  the 
parth*  estimated  breadth  of  the  sides  being  180  mm,  the  transverse 
diameter  through  the  zone  of  involution  at  the  fifth  pair  of  dorsal  and 
eighth  pair  of  lateral  saddles  being  66  nun.  There  are  seven  pairs  of 
divided  saddles.  The  first  laterals  are  quadrifid  on  right  side  and  bifid  on 
the  left  side,  the  second  to  the  fourth  are  (pxadrifid  on  botli  sides,  and  tlie 
fifth  to  the  seventh,  bifid  on  both  sides.  The  next  or  eighth  pair  are  entire. 
The  volution  was  absent  beyond  this  line.  The  outlines  are  obviously 
similar  to  those  of  S.  lenticularis  xav.  splendens,  and  the  dorsal  including 
the  antisiphonal  lobe  also  resemble  that  variety  and  are  more  cross-shaped 
than  in  PI.  IX,  fig.  8,  wdnch  g'ives  the  doi'sals  of  »S'.  lenticularis  variety 
missis.sipjyiensis.     There  are  three  layers  present  in  the  shell. 

A  fragment  of  a  cast  (PI.  VI,  figs.  3,  4),  collection  Yale  Museum, 
No.  200,  from  Birmingham,  N.  J.,  from  the  Lower  or  ^Middle  Gi'eensand 
Marls,  Upper  Cretaceous,  evidently  in  its  ephebic  stage,  shows  sutures  that 
are  quite  different  from  those  of  any  other  form.  The  venter  is  destroyed 
except  in  one  spot,  but  this  is  sufficient  to  show  it  to  be  solid  and  acute. 
The  volution  is  stouter  than  in  typical  lobafits  or  Irnticiilaris.  The  actual 
diameter  from  line  of  involution  to  venter  is  61  mm.,  and  it  was  probably 
a  few  millimeters  deeper;  the  transverse  diameter  here  is  25  mm.,  this 
beino-  also  a  few  millimeters  sliorter  than  the  actual  diameter. 

The  ventral  lobe  is  broad,  and  it  is  also  evident  that  the  siphonal  sad- 
dles are  not  bordered  internally  l)y  pronnnent  marginal  saddles.     There 


SPHENODISCID.E.  81 

are  twelve  saddles  on  the  side  and  there  may  have  been  one  more.  The 
first  four  lateral  saddles  are  similar  to  those  of  lenticularis,  but  are  succeeded 
internally  by  more  pairs  of  divided  saddles,  and  the  dorsal  lobes  and  saddles 
differ.  The  iirst  to  the  third  are  quadrifid;  the  fourth  is  of  same  type,  luit 
has  three  marginals  on  the  outer  arm;  the  fifth  to  the  seventh  are  simply 
bifid;  the  eighth  is  entire;  the  ninth  is  bifid;  the  tenth  and  eleventh  are 
entire  and  plivUiform.  The  lobes  are  all  symmetrically  bifid,  tlie  l)ranches 
subdivided  and  serrated,  but  the  bases  between  saddles  are  entire  on  both 
sides;  even  the  eleventh  lobe  is  bifid  and  has  minute  serrations,  and  all  the 
smaller  internal  lobes  are  short  and  broad.  There  are  ten  narro^^•  j)liylli- 
form  dorsal  saddles  with  entire  bases  in  the  zone  of  involution,  and  prob- 
ably there  were  originally  eleven.  The  lobes  are  broad,  bifid,  and  digitated 
like  the  opposite  external  ones;  the  saddles  alone  are  quite  difterent.  The 
first  dorsals  are  very  narrow,  almost  linear,  and  the  dorsal  lobes  are  bifid, 
narrow,  and  long,  overlapping  as  in  other  species  of  this  genus.  I  hesitate 
to  describe  this  as  a  distinct  species,  because  it  is  a  fragment,  but  its  sutures 
can  not  be  reconciled  with  those  of  any  other  species. 

The  side,  as  shown  in  PI.  VI,  fig.  4,  is  evenly  convex  as  in  S.  stantoni. 

A  specimen  from  the  friable  marls  3  miles  northeast  of  Ripley,  Miss., 
accompanied  a  specimen  described  above  as  S.  knUcularis  var.  mississijypi- 
ensis.  It  was  from  75  to  80  mm.  in  diameter  probably  when  complete.  It 
is  covered  with  nacre,  but  the  sutures  can  be  seen  sufficiently.  At  a  stage 
when  the  side  is  35  mm.  in  breadth  the  sutures  have  the  complex  as])ect  of 
this  species  in  the  first  four  saddles  and  lobes,  the  fifth  to  the  seventh  are 
bifid  on  both  sides,  and  there  are  about  eight  more  entire  saddles.  This 
specimen  appears  at  first  to  be  identical  with  tlie  var.  mississippiensis  from 
the  same  locality,  but  while  the  external  aspect  is  the  same  the  suture  line, 
even  at  this  comparatively  early  age,  is  like  that  of  beecheri 

A  very  fine  cast  from  Mount  Wahallak,  Kemper  County,  Miss.,  col- 
lected by  Frederick  Braun,  of  Brookh'n,  in  arenaceous  rock  in  lower  part 
of  the  Rotten  limestone,  shows  the  sutures  perfectly  and  also  the  inner  part 
of  tlie  living  chamber.     The  latter  is  oue-lialf  of  a  volution  in  leng-th. 

Tlie  suture  shows  eight  divided  saddles  on  each  side  and  the  form 
and  aspect  are  like  those  of  this  species.  This  fossil  lias  folds  on  the 
outer  half  of  the  outer  volution,  the  inner  part  being  smooth  and  the  sides 
evenly  convex.     Whole  diameter,  partly  estimated,  is  145  mm.;  the  diameter 

MON  XLIV — 03 6 


82         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

at  base  of  living-  oliainber  is  120  mm.;  breadtli  of  side  at  this  line  67  mm.,  to 
tlio  shonlder:  umbilicus  (no  shell  present)  8  mm.  Greatest  transverse 
diameter,  23  nnn.,  is  along  the  median  line  in  the  same  plane;  no  .shell 
p]'e.seut. 

Locality:   Fox  Hills,  South  Dakota. 

Age:  Fox  Hills  group. 

Sphenodiscus  konincki  n.  sp.  Hyatt. 
PI.  XII.  tig.  8. 

This  is  a  cast  in  fragmentary  condition  with  one  side  abraded,  but  the 
rio'ht  side  in  excellent  condition.  The  whole  diameter  was  about  150  mm. 
The  side  is  smooth  near  the  undjilical  shoulder  and  has  the  usual  obsoles- 
cent folds  on  the  outer  part  of  the  lateral  zone.  The  suture  figured  shows 
the  very  large  siphonal  saddle.  While  the  other  saddles  and  lobes  are 
similar  to  those  of  S.  leiitiriilans,  they  are  not  identical.  There  are  six 
divided  saddles  on  the  right  side.     Those  of  the  left  side  were  obliterated. 

LocaUty:  Near  Maestricht. 

Age:  Senonian. 

Sphenodiscus  binckhorsti  Bohm. 

Ainiiumctes  pedernalis  Binckhorst,  1873.  Mon.  Gast.  et  Ceph.  du  Limbourg,  pi.  .5a', 

fig.  2  and  od,  fig.  1  (no  others). 
Sphenodiscus  Unckhorstl  Bohm,  1898,  Zeitschr.  Deutsch.  geol  Gesell.,  Vol.  L,  p.  197. 

This  species  from  Limbourg  as  figured  by  Binckhorst  is  a  close  ally  of 
our  American  S.  'plenriseiM,  but  has  only  one  line  of  nodes,  with  costa?  arising 
from  these  and  radiating  outwardl}';  apparenth'  there  is  no  outer  line  of 
nodes.  It  is  said  to  have  been  compared  with  Roemer's  originals.  This 
leads  one  to  think  that  these  must  include  more  than  one  species. 

Sphenodiscus  ubagshi  Grossouvre. 

Spheniidiscus  uhagshl  Grossouvre,  1893,  Ammonites  Craie  superieure,  p.  141,  pi.  9, 
fig.  -4-6. 

This  French  species  is  more  like  our  S.  hhatiis  than  any  other  species, 
l)ut  the  principal  lateral  saddles  have  less  lobate  phylliform  outlines.  The 
sutures  have  the  small  first  lateral  saddles  common  in  this  genus  and  five 
divided  saddles. 

Af)e:  Upper  Campanian  (uppermost  Gretaceous). 


EULOPHOCERATID.E.  83 

Sphenodiscus  rutoti  Grossouvre. 
Sphenodiscus  rututi  Grossouvre,  l81i:3.  Ammonites  Craie  superieiire,  p.  143. 

This  French  species  is  obviously  closely  allied  to  S.  uhagski,  but  the  three 
principal  laterals  are  very  distinct  from  that  and  from  any  of  our  species. 

Age:   Upper  Carapanian  (uppermost  Cretaceous.) 

Sphenodiscus  siva  (Forbes). 

Ammo7iites  siva  Forbes,  1845.  Trans.  Geol.  Soc.  London,  2d  series,  Vol.  VII,  p.  110, 

pi.  7,  fig.  6. 
Sphenodiscus  siva  Kossmat,  1895,  Beitr.  Pal.  und  Geol.  Oesterreich-Ungarns  und  des 
Orients,  Vol.  IX,  pi.  a'2,  tig.  2. 

This  species,  as  figured  by  Forbes,  is  completely  involute,  smooth,  and 
probably  has  an  entire  keel.  It  is  extremely  acute  on  the  venter  and  highly 
compressed.  There  are  three  complex,  narrow,  deeply  cut  derivative  sad- 
dles, with  phylliform  marginals.  The  venter  has  a  prominent  pointed 
siphonal  saddle  according  to  the  figure. 

Agfi:  Valudayur  beds,  Upper  Senonian. 

EULOPHOCERATID2E  Hyatt." 

This  group  appears  to  be  necessary  in  order  to  separate  the  remark- 
able series  of  forms  included  under  this  title  from  the  Coilopoceratidae. 
The  forms  include  Tegocems,  which  was,  according  to  d'Orbigny's  figure, 
a  form  with  a  remarkably  rounded  volution  in  the  gerontic  stage,  but 
having  a  venter  like  that  of  Styracoceras  in  the  ephebic  stage,  and  a  second 
genus,  which  is  exactly  similar  to  Coilopoceras  in  form,  compressed,  and 
witli  an  acute  venter.  All  of  these  have  peculiarly  solid,  low,  broad  sad- 
dles and  short  lobes,  the  marginals  being  simple  and  not  usually  branching, 
but  often  long,  narrow,  and  tongue  shaped.  The  first  two  saddles  may  be 
reckoned  either  as  one  very  broad  saddle  or  as  two,  the  dividing  lobe  being 
small.  The  auxiliaries  are  also  very  peculiar,  and  in  Coilopoceras  the  inner- 
most is  a  long  sweeping  curve.  So  far  as  the  evidence  goes,  Eulojjhoceras 
appears  to  have  had  a  dift'erent  origin  from  Sphenodiscus  and  Coilopoceras, 
as,  indeed,  is  quite  clearly  indicated  by  the  sutures.  Tegoceras  probably 
had  a  solid  keel,  but  no  direct  observations  have  been  made  upon  this 
part  of  its  shell. 

.  "See  note  on  p.  84. 


84         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

The  development  of  Euloplioceras  indicates  quite  clearly  derivation 
from  the  same  common  stock  as  BucJiiceras  and  the  Tissotidpe,  and  it  should 
be  noted  that  the  sutures  are  more  like  those  of  BitcJiiceros,  in  having  very 
laro-e,  broad  first  and  second  lateral  saddles.  The  form  indicated  for  the 
ephebic  stage  of  Tegoceras  in  d'Orbigny's  fig'ure  suggests  tliat  here,  as  in  the 
Tissotida^  and  Coilopoceratidae,  the  more  primitive  species  had  truncated 
venters  with  keels  and  lateral  tubercles. 

TEGOCERAS"  n.  gen.  Hyatt. 

The  curious  form  figured  by  d'Orbigny  as  Ammonites  mosensis  is 
obviously  entirely  distinct  from  any  species  heretofore  described,  so  far  as 
I  know.  Tlie  external  outline  in  the  geroutic  stage  in  section  is  oval,  with 
rounded  venter  and  only  slight  involution.  There  were  obviously  large 
alternating  nodes  on  the  venter  of  the  inner  ephebic  volution  and  a  some- 
what elevated  and  bluntly  subangular  venter.  These  characters  are  com- 
bined with  sutures  having  in  the  gerontic  stage  a  large  first  lateral  saddle 
divided  as  in  gevrilianus,  so  that  it  is  probably  really  two  principal  laterals. 
The  auxiliaries  are  irregular  and  pseudoceratitic  in  outline.  The  peculiar 
crowded,  tongue-like,  elongated,  marginal  saddles  and  lobes  are  similar  to 
those  of  Euloplioceras,  and  it  is  mentioned  in  this  paper  on  that  account 
The  only  species  known  is  the  following: 

TeGOCERAS    MOSEN.se    (d'ORBlGNV). 

A/,ii/ionites  ntoscfiK/'s  d^Ovhignj,  IS-io,  Terr.  Cretace,  pi.  67. 
Age:  Albian. 

LENTICERAS  Gerhardt.' 

This  oenus,  described  bv  Gerhardt  in  his  Kreideformation  in  Venezuela 
and''  Peru,  had  for  its  type  Lenticeras  (A mm.)  andii  (Gabb).  Being  unable 
to  compare  this  with  Gabb's  types  that  have  apparently  disappeared,  it  is 

"Tiyoi,  root". 

''  In  Zittel's  Text-book  of  Palaeontnlogy,  ^'ol.  I,  p.  591),  Professor  Hyatt  refers  this  genus,  together 
with  Paraloiliri'rti.i  and  Pkitijlentkernx,  to  ttie  family  of  Lenticeratida'.  Althougli  the  statement  is 
not  directly  made  that  the  family  is  abandoned,  it  may  be  inferred  from  the  reference  of  Plat i/l mlicerns 
to  Coilopoceratidie,  the  remark  under  Paralenticerax  about  its  attinity  for  Eulophorems,  and  the  fact 
that  the  manuscript  was  arranged  as  now  published  with  Lenticerox  and  Puralentlceras  between 
Te()ocerus  and  Euloplioceras. — T.  W.  S. 

''Neues.labrbuch  fiir  Min.,  (ieol.,  und  Pal.,  Beil.-B.l.  XI,  1.h;i7-V18,  ji.  81,  pi.  1,  fig.  9. 


EULOPHOCEKATID.E.  85 

not  practicable  to  say  that  these  species  are  identical,  as  su[)posed  by 
Gerhardt.  The  drawings  certainly  differ  materially.  The  sutures  are 
more  like  those  of  Paralenticeras  than  those  of  any  other  genus  that  I 
know.  The  siphonal  saddle  is  very  large,  the  first  lateral  saddle  has  three 
long  arms,  the  outer  one  the  shortest  and  the  inner  one  the  longest.  The 
first  lateral  lobe  is  narrow  and  trifid  with  long  bifid  arms.  The  outei-  lobes 
are  narrow  also,  whereas  the  saddles  are  very  broad  and  solid  and  have 
short  rounded  marginals. 

The  volutions  are  depressed,  helmet  shaped  in  section,  and  very  broad, 
without  keels,  but  have  smooth  shells  with  broad  fold-like  knobs  on  the 
umbilical  shoulders. 

PARALENTICERAS  Hj^att. 

This  is  a  highly  compressed  involute  smooth  shell  with  sutures  unlike 
those  of  any  other  known  genus  except  Lenticeras.  Although  so  compressed 
and  smooth  that  it  resembles  PlatyJentkeras,  it  is  obviously  a  member  of  the 
same  genetic  series  as  Lenticeras.  The  excessiveh^  elongated  and  club- 
shaped  marginals  also  indicate  affinity  for  Eulophoceras. 

The  genus  was  mentioned  in  Zittel's  Text-book,  Cephalopoda,  page 
590,  and  placed  in  its  proper  relationship  to  Lenticeras. 

The  sutures  have  the  same  liroad  first  lateral  saddle  with  three  arms, 
the  shortest  next  the  venter,  as  in  Lenticeras,  and  similar  second  and  third 
laterals.  All  the  outlines  are  also  of  the  general  outline  according  to 
Gerhardt's  figui'es. 

I  fail  to  recognize  auv  special  resemblances  to  the  sutures  of  Aninion- 
ites  chfpeiforniis  d'Orl).,  wliich  has  a  type  of  suture  found  in  Coilopoceras 
and  its  allies. 

Onlv  one  species  is  known  to  me,  P.  (Aiii(ilflieits)  sieversi  Gerhardt." 

EULUPH0(;ERAS''  n.  gen.  Hyatt. 

This   genus   is  proposed   for   shells   similar  to  Plati/lenticeras,  but  the 
sutures  ol)viouslv  have  onlv  two  })rincipal  laterals,  derived  from  the  j)rinii- 
tive  first  lateral  saddle,  and  onh'  a  few  broad  auxiliary  saddles,  tlie  inner 
most  being  extremely  broad. 

Only  one  species  is  positively  known  at  present  to  be  in  this  genus. 


«Neues  Jahrbuch  fur  Min.,  Geol.,  und  Pal.,  Beil.-Bd.  XI,  1897-98,  p.  79,  pi.  1,  fig.  5. 
I'EvXutpoi,  handsome  crest. 


86  PSEUDOCERATITES  OF  THE  CRETAC;EOUS. 

EULOPHOCERAS    NATALENSE    H,    sp.    Hvatt. 

PI.  XI.  tigs.  lm;. 

This  species  is  founded  upon  a  fragment  in  the  collection  of  the  Yale 
Museum.  It  is  a  bare  cast  on  one  side  with  the  shell  preserved  on  the 
opposite,  right  side,  and  on  venter.  Diameter,  partly  estimated,  is  164 
mm.  (actual  diameter  155  mm.).  There  is  no  uml>ilicus,  this  being  practi- 
cally sealed  up  Ijy  the  growth  of  shell  on  one  side,  and  is  of  course  very 
small,  where  cleaned  out  on  the  other  side.  There  are  faint  folds  on  both 
shell  and  cast.  The  folds  occupy  the  sides  and  are  not  confined  to  the 
outer  or  inner  parts  of  the  lateral  surfaces,  although  more  j^i'ominent  along 
the  centran  lateral  lines. 

The  keel  is  solid  in  the  younger  stages  (PI.  XI,  figs.  5,  6)  and  then 
becomes  apparently  hollow.  The  proof  of  this  is  not  al)solutely  clear,  but 
in  each  volution  of  the  section  there  is  a  ]iartition  of  shell  outside  of  the 
siphuncle.  In  the  upper  tip  of  the  section  of  the  volution  next  to  the  last 
a  partition  was  also  present,  but  this  is  apparently  a  section  of  the  sejDtum 
itself,  and  what  seemed  to  be  the  siphuncle  is  represented  on  the  right  and 
above  this  partition.  If  this  be  correct  the  keel  is  solid  at  this  age  and 
remains  in  this  condition  in  the  last  volution.  The  siphuncle  is  not  present 
in  this  last  volution,  but  as  in  the  section  of  the  next  younger  volution 
above  described  the  common  matrix  fills  the  interior  completely  and  on  the 
outer  exposed  edge  the  sutures  run  against  the  solid  interior  of  the  thick 
deposits  of  the  keel.  In  the  younger  whorls  the  space  between  the  parti- 
tion above  the  siphuncle  and  tlie  keel  is  filled,  as  in  the  interior  of  the 
siphuncle,  by  dark  transparent  calcspar.  There  is,  however,  no  black  layer 
present  above  the  siphuncle,  as  in  the  Jurassic  forms,  that  have  hollow  keels 

The  sutures  are  extraordinary.  They  are  so  excessively  overlapped 
that  there  are  two  second  lateral  lobes  telescoped  into  every  third  one,  so 
that  one  has  to  disentangle  the  lines  of  three  consecutive  sutures  in  marking 
out  this  lobe.  It  becomes  necessary,  in  fact,  to  infer  outlines  that  can  not 
be  seen,  the  sutures  having  in  some  parts  necessarily  passed  along  the 
same  lines  and  can  not  be  separated  by  the  eye.  The  first  to  third  lateral 
saddles  are  broad  and  have  numerous  long  tongue-sliaped  marginal  saddles. 
The  fourth  lateral  saddle  is  also  broad,  deeply  bifid,  the  outer  arm  entire, 
the  inner  bifid.  About  half  of  a  volutifin  earlier  this  saddle  is  much  nar- 
rower, and  is  probablv  still  smaller  at  youngvr  stages.     The  fifth  is  al.-<o  a 


EULOPHOCERATID.E.  87 

broad  saddle,  but  shorter  thau  the  fourth  and  has  two  arms,  the  outer 
bifid,  the  inner  trifid.  The  sixth  is  a  long-  entire  renniant  of  the  primitive 
second  lateral  saddles  of  the  nepionic  stage  occupying-  the  umbilicus.  The 
inner  part  of  the  outline  of  this  saddle  is  faintly  concave,  especially  where 
it  crosses  the  shoulder,  but  no  definite  lobe  is  formed.  The  lateral  lobes 
are  cut  up  by  marginals  on  their  entire  outlines.  The  first  laterals  are 
about  as  long-  as  the  short  narrow  arms  of  the?  ventral;  the  second  laterals 
are  about  a  third  longer  and  fully  twice  as  broad;  the  third  laterals  are 
about  the  same  size  and  length  as  the  first  laterals;  the  fourth  are  shorter 
and  about  the  same  breadth;  the  fifth  is  narrow  and  divided  by  two  minute 
tono-ue-like  saddles.  These  form  a  column  near  the  vnnbilical  shoulder  of 
the  cast. 

On  the  right  side  the  third  lateral  or  first  auxiliary  saddle  is  very 
mucli  smaller  at  the  same  age,  and  apparently  subdivided  with  at  least  one 
dividing-  lobe,  giving  one  more  lobe  and  one  more  saddle  on  this  side.  The 
fifth  is  also  narrower  and  has  a  simple  trifid  outline.  The  remaining 
saddles  and  lobes  nlso  differ,  and  in  fact  this  side  of  this  specimen  might 
be  described  as  belonging  to  a  distinct  species.  The  first  and  second 
laterals  are  larger  and  the  marginals  fewer  in  nuniV)ei-,  but  tlie  jn-incipal 
difference  lies  iu  the  second  or  primitive  lateral  lobe.  This  is  bifid,  divided 
bv  one  very  large  median  marginal  saddle.  There  are,  however,  but  two 
principal  lateral  saddles  on  both  sides. 

The  outlines  of  these  sutures  are  entirely  distinct  from  those  of  any 
species  of  Sphenodiscus.  The  bodies  of  the  saddles  are  solid  and  the 
complicated  outlines  are  made  bv  the  outgrowth  of  long  tongue-like 
marginals,  the  lobes  l)eing  divided *in  the  same  way.  The  only  suture  so 
far  figured  having  a  similar  outline  is  that  of  Tegoceras  mosense. 

The  ventral  lobe  is  very  broad,  the  outline  sinuous,  tlie  center 
occupied  by  a  small  lobe  divided  by  a  sharp  minute  saddle.  There  are 
two  arms  to  the  ventral  lobe,  short,  narrow,  and  bifid,  and  parallel  with  the 
venter.  These  are  quite  different  from  the  usual  spreading-  arms  of  this 
lobe  in  Sphenodiscus  and  Goilopocexas.  The  auxiliary  saddles  are  even 
more  distinct  as  described  above  and  together  with  the  number  of  the 
j)rincipal  lateral  saddles  show  that  we  are  dealing  with  a  .species  that  can 
not  be  included  in  Sphenodiscus  nor  iu  CoUopoceras. 

Locality:  Port  Natal,  South  Africa. 

Afje:   Upper  Cretaceous. 


88  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

COILOPOCERATID2E   Hyatt. 

This  includes  g-enera  having-  the  primitive  tirst  hiteral  Siiddles  far  more 
variable  in  development  than  in  Sphenodiscidje.  Aconeceras  has  only  one 
long  deeply  divided  first  lateral.  Plafi/lenfireras  and  Cnilojiorori.^)  liave 
three  according  to  the  method  of  reckoning  adopted  below,  but  the 
elements  are  the  same  as  in  Aconeceras.  Aconeceras,  Sfyracoceras,  and 
Platylenticeras  probably  have  solid  keels,  although  there  are  no  observations 
on  this  point  that  can  be  quoted. 

The  development  and  adult  form  of  Styracoceras  indicate  that  the 
niore  j^rimitive  forms  of  this  family  had  truncated  venters  with  keels  and 
lateral  tubercles,  and  were  similar  in  external  aspect  to  Buchiceras. 

Coilopoceras  has  a  hollow  keel.  The  sutures  and  development  at  iirst 
seem  to  place  it  in  tiie  same  group  with  Sphenodiscus,  but  the  two  principal 
lateral  saddles,  the  median  lateral  lobe  (second  lateral  lobe)  with  long 
tongue-shaped  marginal  saddles,  and  the  aspect  of  the  auxiliaries  in  the 
young  indicate  association  in  the  same  family  with  Aconeceras. 

These  remarks  show  that  while  these  genera  are  sufficienth*  distinct, 
their  association  in  a  group  together  is  made  more  to  call  attention  to 
certain  sviggestive  similarities  than  with  any  idea  that  they  realh'  belong 
together  exactly  as  described  below. 

The  evidence  that  this  family  was  directly  derived  from  Pht/Iloceras  or 
some  similar  form  rests  upon  the  general  outlines  of  the  saddles,  whicli  are 
phylliform,  especially  in  the  neighborhood  of  the  umbilici,  and  the  widely 
spreading  and  })eculiar  lobes.  The  dorsal  sutures  are  as  usual  less  changed 
than  the  external  inflections  and  these  have  almost  exclusively  phylliform 
outlines  like  those  of  Phylloceratida.  The  antisiphonal  has  a  long  narrow 
form  with  a,  bifid  i^nd  and  although  it  is  serrated  or  slightly  IjrancliinL;-  and 
not  so  simple  as  in  FhijUoceras,  it  has  a  similar  form. 

As  mentioned  in  the  generic  description  of  Aconeceras  the  sutures  of 
A.  nisum  make  a  nearer  approach  to  those  of  Pliylloceras  than  any  other 
genera  of  this  group  or  any  others  except  the  Sphenodiscidse." 

PLATYLENTICERAS  Hyatt. 

This  geuus  was  mentioned  in  Zittel's  Text-book,  page  590,  by  the  author 
and  the  type  given  was  the  same  species  cited  below.     The  sutures  are 

«  The  manuscript  of  this  last  paragraph  bears  an  interrogation  mark  on  the  margin. — T.  W.  .S. 


COILOPOCERATID.E.  89 

similar  to  those  of  Collopoceyas  but  are  still  more  like  those  Styracoceras 
halduri.  The  siphonal  saddles  are  small  and  bitid  in  these  two  genera. 
The  small  first  lateral  lobes  may  be  reckoned  either  as  mere  marginals  in 
this  genus  dividing  the  first  lateral  saddles  equally  or  as  true  first  laterals. 
The  two  small  saddles  coming  next  to  these  resemble  the  corresponding 
saddles  in  Coilopoceras.  Uhlig  in  his  Die  Cephalopodenfauna  der  Teschener 
und  Grodischter  Schichten"  figures  several  species  mentioned  below,  one  of 
which  has  a  rounded  venter  with  the  usual  smooth  sides  and  characteristic 
sutures  of  this  genus.  Uhlig  takes  the  same  position  that  has  been  here 
inde})endently  assumed,  namely,  that  the  sutures  are  similar  to  those  of  Sti/r. 
halduri  (Keyserling),  and  that  the  affinit}^  of  this  genus  for  Mojsisovicsia 
is  shown  by  the  development  of  one  of  his  species  which  has  a  rounded 
venter  until  a  late  stage.  The  sutures  and  the  affinities  of  this  fossil  for 
P.  heteropleurum  show  that  this  is  a  prolonged,  immature,  or  arrested  condi- 
tion of  ontogenic  development,  and  therefore  an  indicaticm  of  remote  rather 
than  proximate  derivation  from  Mojsisovicsia,  whose  sutures  are  widely 
d'fi"erent.  The  section  of  I*,  heteropleurum  given  by  Struckmann''  shows  that 
the  transition  from  a  rounded  to  an  acute  venter  probably  takes  place 
directly  at  a  comparatively  early  stage,  as  might  be  imagined  after  study 
ing  the  ontogeny  of  P.  pseudofjrasianum.  This  fact  shows  that  the  resem- 
blances of  the  sutures  wdth  those  of  Styracoceras  have  no  genetic  significance 
because  the  extraordinary  and  complex  ontogeny  of  that  genus  indicates 
very  distinct  aifinities. 

Platylenticeras  heteropleurum  (Xeumayr  and  Uhlig). 

Oxynoticeras  hetd^'opleurum  Neumayr  and  UhHg,  1881,  Palteontogr. ,  Vol.  XXVII, 
pi.  15,  figs.  1,  2. 

Tliis  species  has  smooth  compressed  volutions  but  the  involution  is  not 
sufiicient  to  cover  the  sides  and  the  umbilici  are  quite  large.  The  keel  is 
acute  and  so  far  as  can  be  seen  iu  the  figures  is  apparently  solid.  The 
sutures  as  drawn  by  the  authors  cited  are  not  at  all  like  those  of  true  Oxyno- 
ticeras,  which  have  only  one  first  lateral  saddle,  but  are  similar  to  those  of 
Styracoceras  halduri,  as  stated  above.     It  is  not  practicable  to  determine 


«Denksch.  K.  Akad.  Wiss.,  Wien,  Vol.  LXXII,  1901. 

''.lahrb.  K.  preugs.  geol.  Landesanstalt,  1889,  p.  71,  pi.  11. 


90         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

wlietlier  Ammonites  heteropleiirus  Stnickmaiin"  and  Amm.  gevrUianus  Dunker,* 
whicli  were  found  partly  in  the  same  localities  in  north  Germany,  are 
identical  or  not,  but  they  are  probably  the  same. 

Locality:  Near  Springe,  Hanover. 

Age:  Neocomian. 

Platylenticeras  pseudogeasianum  (Uhlig). 

O.vynoticeras  pseudograsianum  UhUg,  1901,  Denkscli.  K.  Akad.  Wiss.,  Wien,  Vol. 
LXXII,  p.  25,  pi.  '1. 

This  is  a  really  discoidal  shell  with  a  much  larger  umbilicus  than  other 
species  of  this  genus,  and  therefore  making  a  nearer  approach  to  the  radical 
form  of  Mojsisovicsia,  but  it  has  on  the  other  hand  the  characteristic  sutures 
of  the  P.  heteropleurnm  type;  that  it  should  have  a  rounder  venter  until  a 
late  stage  is  quite  consistent  with  its  noniuvolute  discoidal  aspect." 

Locality:  Nieder-Lischna. 

Age:  Valangian  (Lower  Neocomian). 

Platylenticeras  gevrilianum  (d'Orbigny). 

Ammonites  gevrUianus  d'Orbigny,  1840.  Terr.  Cretace,  pi.  -43. 

This  species  was  noted  by  Neumayr  and  Uhlig,  in  their  Ammouitiden 
aus  den  Hilsbildungen,  as  having  similar  sutures  and  similar  external  char- 
acters to  Platylenticeras  heteropleiinim,  which  is,  however,  in  my  opinion 
quite  distinct.  Aconeceras  nisum  was  also  cited  by  them  as  an  ally,  but  this 
has  only  one  principal  lirst  lateral  and  the  resemblances  exist  only  in  the 
external  cliaracters.  Amm.  marcousamis,  also  cited  by  them  as  an  ally,  has 
only  one  large  bifid  first  lateral  and  has  a  depressed  rounded  volution  and 
tubercles  like  Packydiscus. 

Age:  Aptian. 

"Jahrb.  K.  preuss.  geol.  Landesanstalt,  1889,  p.  71,  pi.  11,  figs.  3,  4. 

sPateontogrr.,  Vol.  I,  1851,  p.  324,  pi.  41,  figs.  21-24. 

'The  other  species  mentioned  and  figured  by  Uhlig  are  not  named.  They  are  iloser  to  th^- 
involute  character  of  P.  heteropleurum,  but  one  of  these,  Oxt/n.  cf.  heteropleitrum,  pi.  2,  fig.  2,  has  three 
principal  saddles  instead  of  two  and  is  considerably  less  involute  than  that  species. 


COILOPOCERATID.E.  91 

COILOPOCERAS  "  n.  gen.  Hyatt. 

This  genus  inclnd'^s  species  formerly  associated  with  SplienocUsais, 
which,  however,  differ  so  that  they  are  easily  separated.  The  development 
and  form  are  closely  similar;  that  is  to  say,  the  shell  develops  directly 
from  the  rounded  nepionic  volutions  into  a  helmet-shaped  whorl  in  section 
having  subacute  venter  which  becomes  more  acute  with  age.  In  the  three 
forms" described  below  in  tiie  neanic  and  adult  stages,  the  volutions  are 
somewhat  less  compressed  than  in  species  of  Sphenodiscus,  but  this  is  prob- 
ably only  a  specific  character. 

The  sutures  differ  in  having  broad  first  lateral  saddles  with  a  peculiar 
large  internal  arm  or  marginal  saddle,  and  the  first  and  second  laterals,  when 
the*^ second  are  present,  are  narrow  and  very  distinct  from  the  first  laterals 
on.the  outer  side  and  the  first  large  auxiliary  saddles  on  the  inner  side. 
There  are  but  two  secondary  lateral  saddles,  the  first  and  second,  derived 
from  the  division  of  the  primitive  first  laterals  in  C.  colleti,  the  type  of  the 
genus,  but  this  form  is  in  an  early  ephebic  substage  and  the  aspect  of  C. 
novimexicamnu  at  a  somewhat  older  stage  shows  that  there  is  an  approxima- 
tion to  the  trisellate  condition.  This  trisellate  or  placenticeran  aspect  of 
the  principal  or  first  outer  saddles,  derived  from  the  division  of  the  primi- 
tive first  lateral  saddles,  is  still  more  marked  in  C.  springeri  The  hollow 
keel  is  remarkably  distinct.  When  the  shell  is  removed,  the  siphuncle  is 
covered  only  with  a  very  thin  layer  of  the  fossilizing  sediment,  and  this 
organ  is  apt  t<i  be  exposed  on  the  casts  and  is  often  absent  in  more  or  less 
worn  specimens,  leaving  the  venter  deeply  channeled.  This  last  accident 
is  of  rare  occurrence  among  forms  with  solid  keels.  The  siplrancle  is  also 
laro-er  and  thicker  walled  than  in  Sphenodiscm. 

CoiLOPOCERAS  COLLETI  n.  sp.  Hyatt. 

PI.  X,  tigs.  5-21:  PI.  XI.  tig.  1. 

This  species  is  easily  distinguished  by  comparison  with  its  nearest 
affine,  Coilopoceras  mvimexicammi.  It  has  stouter  volutions,  a  more  open 
umbilicus,  the  venter  is  blunter,  and  in  the  young,  at  any  rate,  it  has  larger, 
stouter  fold-like  costs;,  one  long  one  reaching  to  the  umbilical  shoulder, 

a  KmXooTTOi,  hollow. 


92  PSEUDOCERATITES  OF  THE  (JRETACEOUS. 

aud  ail  alternating  shorter  one.  This  last  series  (lisa})pears  in  the  last  part 
of  the  outer  volution  of  the  specimen  descrllied,  leaving  a  series  of  single 
costfE.  These  may  perhaps  be  obsolete  or  obsolescent  in  older  specimens. 
There  is  a  decided  aspect  of  bifurcation  in  the  earliest  stage  ol)served  when 
from  line  of  involution  to  venter  the  cast  of  tlie  volution  is  1.5  to  20  nmi., 
l)ut  there  are  no  tubercles.  The  whole  diameter  of  this  o;ist  is  67  mm. 
The  outer  volution  at  largest  end  from  line  of  involution  to  venter  is  37  mm.; 
without  the  shell  the  umbilicus  is  7  mm.  on  one  side  and  .S  mm.  on  the 
other  side;  with  the  shell  it  would  be  5  mm.  on  one  side  and  C  mm.  on  tlie 
other.  The  greatest  transverse  diameter  is  about  one-third  of  lateral  zone 
distant  from  umbilicus  and  is  for  thickest  part  18  mm.,  and  opposite,  cor- 
responding to  ventro-dorsal  diameter  above  given,  it  is  11  mm.,  both 
measurements  being  between  the  costse.  The  costse  are  more  prominent  on 
the  middle  and  inner  parts  of  the  sides  than  on  tlie  outer,  and  broaden 
out  toward  the  venter,  disappearing  near  the  solid  edge  somewhat  abruptly 
on  the  younger  parts  and  more  gradually  along  the  older  part  of  this 
volution. 

The  first  lateral  saddles  are  broad  and  short  trifid  on  the  right  side, 
with  a  small  outer  marginal  saddle  and  quadrifid  on  the  side  figured  (PI. 
X,  fio-.  7),  with  an  inner  accessory  large  marginal  saddle  dependent  on  the 
first  laterals.  The  second  laterals  are  single,  short,  but  slender  saddles, 
with  phylliform  bases,  which  are  only  slightly  indented  at  the  age  observed 
The  third  laterals  are  only  about  a  third  longer  than  these,  and,  although 
overlapping,  are  easily  separated.  The  outlines  are  irregular  and  deeply 
indented  by  two  marginal  lobes  and  other  accessoiy  lobes.  Tlie  fourth  aud 
fifth  laterals  are  phylliform,  with  the  bases  indented  by  a  number  of 
marginal  lobes,  apparently  entire  and  small.  The  sixth  and  seventh  laterals 
are  faintly  trifid.  The  almost  entire  aspect  of  these  saddles  is  due  to  slight 
abrasion.  On  the  youngest  part  of  this  volution  (PI.  X,  fig.  9)  all  of  the 
saddles  are  entire  except  first  to  third,  the  cast  here  being  16.5  mm.  in 
breadth  from  line  of  involution  to  venter;  the  outlines  are  perfect. 

The  ventral  saddles  are  more  like  those  of  Sphenodiscus  than  in 
novimexicantm,  and  have  rounded  mnrginal  saddles  at  the  inner  angles. 
The  first  lateral  lobes  are  of  about  tlie  same  length  as  the  arms  of  the 
ventral  lobe,  both  of  them  trifid  and  with  accessory  marginal  lobes  orad  of 
these.    The  second  laterals  are  the  deepest  lobes,  and  represent  the  primitive 


COILOPOCERATID.E.  93 

lateral.  They  are  bitid  and  about  twice  as  long  as  the  third,  the  arms  and 
sides  being  cut  up  by  marginals.  The  remaining  lobes  are  narrow  as 
compared  with  the  saddles,  and  irregularly  denticulated.  I  could  not  tell 
whether  they  were  of  the  tritid  or  bifid  type,  or  both  mixed.  There  were 
eight  lobes,  the  line  of  involution  being-  occupied  by  a  saddle. 

The  venter  is  capped  b}'  a  hollow  keel,  as  in  novimejicammi,  and  in  this 
species  there  is  the  plug,  the  dark  layer,  and  an  inner-shell  layer,  upon 
which  tlie  ventral  saddles  and  lobes  abut. 

The  sutures  are  metre  like  those  of  novimexicaniiitt  than  any  other 
species,  and  I  at  first  considered  this  to  be  the  young  of  that  species;  but  the 
difference  in  these  and  in  the  external  characters  at  the  same  asre  are  fiir  too 
marked. 

The  saddles  and  lobes  are  all  shorter  than  in  iiovimexicanmii  and 
overlap  a  trifle  only  from  the  fourth  lateral  to  the  umbilicus.  They  are 
also  much  less  complicated  in  outline  or  less  cut  into  b\'  marginal  lobes,  and 
less  distinctly  2)hylliform. 

The  young  in  section,  so  far  as  seen,  showed  the  same  general 
development  as  in  Sphenodiscus,  but  the  division  of  the  primitive  first  laterals 
took  place  early  in  the  neanic  stage. 

The  figures  (PI.  X,  figs.  10-21)  give  the  stages  as  far  as  these  could 
be  studied.  The  protoconch  is  stout  and  slightly  scaphitoid  or  irregular  in 
shape,  like  many  other  Cretaceous  forms  The  second  suture  had  a  miniite 
siphonal  saddle  that  was  distinctly  seen  by  a  side  light.  Fig.  11  shows 
the  deepening  of  the  antisiplional  and  the  beginning  of  the  two  first  dorsal 
saddles  on  the  first  quarter  of  the  second  volution.  Fig.  11a  shows  the 
lengthening  of  the  antisi})honal,  the  incoming  of  two  saddles  and  the 
beginning  of  a  third  on  the  dorsum,  the  incipient  stages  of  division  of 
the  primitive  second  lateral  into  four  saddles  of  the  auxiliary  system  and 
the  arising  of  the  second  lateral  saddle  on  the  inner  side  of  the  ^jrimitiA-e 
first  lateral  saddle.  Fig.  12  shows  the  progressive  lengthening  of  the 
antisiphonal,  the  presence  of  a  third  jiair  of  fully  developed  saddles  on  the 
dorsum,  the  division  of  the  primitive  second  lateral  into  four,  the  definite 
separation  of  the  second  lateral  saddle,  and  the  incipient  stage  of  the  great 
inner  branch  of  the  first  lateral  saddle;  also  the  first  appearance  of  the 
smaller  marginals  on  the  outer  side  of  the  base  of  the  same 


94         PSEUDOCERATITES  OF  THE  CRETACEOUS. 

This  specimen,  therefore,  affords  clear  ideas  of  the  mode  of  development 
of  the  fnll-grown  sutures  in  this  form  and  also  in  the  group  to  which  it 
belongs. 

Locality:  Near  Carthage,  N.  Mex. 

Age:  Colorado  group,  Upper  Cretaceous. 

COILOPOCERAS    NOVIMEXICANUM  1\.  Sp.   Hyatt. 

PI.  X,  figs.  1-4. 

This  species  apj^ears  to  be  more  like  Sphenodisciis  lenticularis  Meek 
than  anv  other  at  first  sight,  but  the  sutures  and  other  characters  are  .so 
dissimilar  that  this  impression  is  easily  corrected. 

The  cast  in  hand  is  93  mm.  in  diameter  and,  allowing  for  siphuncle  on 
one  side  and  cre.sts  on  both  sides,  it  would  be,  when  perfect,  alxuit  96  mm. 
The  transverse  diameter  of  the  outer  volution  is  56  mm.,  the  umbilicus  is 
about  1..5  mm.,  and  the  outer  volution  below  on  same  line  is  34  ram.  without 
siphuncle  and  crest,  which  would  make  it  with  both  about  35.5  mm.  The 
transverse  diameter,  about  the  middle  of  the  lateral  zone,  is  23  ram.  for  the 
laro-est,  oldest  part  of  the  volution  and  15  mra.  for  the  sraaller,  younger 
part  opposite  this.  The  latter  had  the  shell  on  both  sides,  and  deducting 
this  it  would  be  14  mra. 

While  the  form  and  aspect  were  the  same  as  in  most  other  species  of 
this  genus,  it  has  very  faint  fold-like  costae  on  the  outer  part  of  the  last  half 
of  the  outer  volution  and  more  decided  and  more  fold-like  costations  upon 
the  younger  portion  and  on  first  quarter  of  the  exposed  volution;  these  last 
reach  to  the  umbilical  shoulder. 

The  venter  is  subacute,  with  blunted,  narrow  crest,  and  on  either  side 
of  this  lateral  zones  are  slightl}-  concave  on  the  entire  outer  volution.  The 
shell  vaulted  over  a  clear  space  above  the  si})huncle,  the  hollow  keel,  and 
this  was  filled  by  clear,  crystalline  liraestone  different  from  the  matrix, 
and  there  was  a  black  layer  over  the  siphuncle.  P^arther  out  a  part  of  the 
black  layer  was  found  to  consist  of  black  dendritic  oxide  of  iron.  The 
sutures  are  equally  peculiar.  Upon  closer  examination  it  is  seen  that  the 
resemblances  to  Placenticeras  are  due  to  the  small  size  of  marginal  saddles, 
the  soliditv  of  the  fourth  lateral  saddles  and  the  greater  complication  of 
tlie  smaller  saddles  than  in  Sphenodiscus.     There  are,  however,  but  two 


COILOPOCEKATID.E.  95 

secoudarv  lateral  saddles,  although  the  deep  division  and  length  of  the 
inner  branch  of  the  first  laterals  make  apparently  three  saddles.  The  outer 
branch  of  the  first  lateral  saddles  is  narrow,  long,  much  cut  up  by  marginal 
lobes,  bifid,  and  has  phvlliforni  elongated  marginal  saddles.  They  slightly 
overlap  the  branches  of  the  ventral  lobe,  'except  in  the  two  sutures  figured. 
A  large  marginal  springs  from  their  orad  jjarts  inward,  forming  a  narrow 
saddle  with  phylliform  single  base,  undivided  on  the  younger  ])arts  of  the 
volution  and  beginning  to  have  a  small  lobe  on  outer  side  in  older  parts 
of  same.  These  are  much  longer  than  in  colleti,  are  attenuated  and  cut 
into  by  marginal  lobes,  and  would  usually  be  counted  as  the  second  laterals. 
They  do  not  reacli  to  the  next  sutures  and  are  separated  by  bare  spaces 
from  the  outlines  of  the  second  lateral  lobes.  The  pointed  aspect  of  the 
marginals  is  noted  in  PI.  X,  fig.  4,  but  the  slightest  abrasion  would  obliterate 
such  marks  and  make  all  the  marginals  appear  to  be  rounded,  as  they  did 
to  me  at  first. 

The  second  laterals  are  nearly  all  on  a  level  with  these  inne)-  branches 
of  the  first  and  have  solid  elongated  bases,  which  are  cut  into  only  by 
small  pointed  marginal  lobes  and  consequently  subphylliform,  but  apicad  of 
these  there  .are  on  each  saddle  two  projecting  phylliform  branches.  The 
third  laterals,  first  auxiliaries,  are  fully  one-third  longer  than  the  second 
and  broad  and  solid  throughout;  the  apical  openings  are  not  contracted, 
their  marginal  saddles  and  lobes  being  small  and  short.  The  extraordinary 
length  of  these  saddles  causes  them  to  overlap  the  inner  outlines  of  the 
third  lateral  lobe  so  much  that  one  is  apt,  unless  aware  of  this,  to  confuse 
two  sutures  and  consider  this  saddle  short  and  broad.  The  remaining 
saddles  decrease  in  length  to  the  umbilicus.  The  fourth  are  like  the 
third  in  aspect;  the  fifth  are  slender,  phylliform,  and  bifid;  the  sixth  are 
slender,  single,  and  phylliform ;  the  seventh  less  elongated,  less  slender,  but 
phvlliforni,  and  near  the  umbilical  shoulders.  On  the  umbilical  zone  there 
are  two  rows  of  saddles  visil)le  on  the  last  part  of  the  outer  volution,  having 
still  the  I'ounded  phylliform  bases  of  the  Sphenodiscus  type.  The  siphonal 
saddles  are  quite  distinct,  larger  and  more  prominent  and  unlike  those  of 
any  other  allied  species. 

The  ventral  lobe  is  similar  to  that  of  Sphenodiscus  lenticularis,  but  has 
spreading  trifid  arms.  The  first  and  second  lateral  lobes  are  narrow.  The 
first  is  decidedly  bifid,  the  second  is  but  a  shade  longer  than  the  first,  and 


9(3  PSEUDOCERATITES  OF  THE  CRP:TACE01TS. 

the  sutures  have  to  be  perfect  to  see  this  clearly.  The  third  is  about 
one-half  the  length  of  the  second,  and  from  this  one  the  decrease  in  length 
is  gradual  to  the  lines  of  involution.  The  third,  fourth,  and  riftli  lateral 
lobes  are  broader  in  proj)ortion  and  correlate  with  the  forms  of  the 
accompanying  saddles.  There  are  eight  lobes  and  nine  saddles  on  the 
oldest  jiarts  of  this  volution,  the  seventh  lobe  being  on  the  umloilical 
shoulder. 

The  septa  are  concave  along  the  median  plane,  being  convex  only  at 
the  ventral  and  antisiphonal  lobes.  The  large  third  saddles,  the  first  of 
the  auxiliary  series,  correspond  to  the  iirst  pair  of  dorsals  and  are  connected 
with  them  so  that  the  number  of  saddles  on  the  dorsum  is  the  same  as  the 
number  of  lateral  saddles,  or  six,  exclusive  of  the  saddle  on  the  line  of 
involution.     The  details  of  their  curves  could  not  be  seen. 

Localitij:  Near  Carthage,  N.  Mex. 

Age:  Colorado  group.  Upper  Ci'etaceous. 

COILOPOCEKAS    SPRINGERI  U.  sp.  Hyatt. 
PI.  XII.  tigs.  1-3. 

This  superb  specimen,  presented  to  the  Museum  of  Comparative 
Zoology  by  Frank  Springer,  of  Las  Vegas,  the  well-known  student  of 
crinoids,  appears  to  liave  characters  so  distinct  that  they  can  not  be 
accounted  for  bv  the  extreme  size  and  age  of  this  specimen.  It  is  4(X) 
nun.  in  diameter.  The  last  part  of  outer  volution  from  lines  of  involution 
to  venter,  which  is  slightly  truncated  by  abrasion,  is  225  mm.,  and  half  of 
a  volution  3"ounger  it  is  196  mm.  This,  judging  from  thickness  of  the  shell 
on  younger  part  (5  mm.)  and  si])huncle  at  this  part  7  mm.  in  diameter,  has 
lost  12  to  15  mm.,  and  to  this  nuist  be  added  shell  in  the  umbilicus,  which 
was  5  mm.  At  the  last  ])ai't  of  the  second  quarter  of  this  volution,  where 
sutures  were  studied,  the  volution  was  195  nun.  in  breadth;  tlie  allowance 
of  5  mm.  for  shell  on  venter  and  of  3  mm.  for  shell  in  undjilicus  makes  the 
volution  when  complete  203  mm.  The  actual  measure  of  same  diameter 
near  beo-inning"  of  first  (luarter,  which  was  entirely  covered  liv  shell,  was 
149  mm.  The  inner  layer  of  the  shell  was  not  present  in  umbilicus  and 
probably  added  2  nun.  to  this  measurement. 

There  is  onh-  a   small   ))art   of  the   living   cliamlier  left  on  this  large 


COILOPOCERATID.E.  97 

specimen,  and  its  original  length  is  not  clearly  indicated  by  any  niai'ks  on 
the  exposed  volution.  The  shell  is  only  partly  presei'ved,  but  it  is  sufficient 
to  enable  one  to  state  that  there  are  no  tubercles  nor  distinct  costae  on 
either  shell  or  cast. 

The  venter  is  subacute  and  appeared  at  first  to  be  solid,  but  close 
examination  showed  a  small  core  of  light-colored  filling-  and  a  fine  darker 
layer  between  this  and  the  large  siphuncle.  The  small  size  of  the  core  was 
due  to  the  great  age  of  the  specimen,  and  probably  at  a  still  older  age  the 
keel  was  entirely  solid.  The  last  part  of  exposed  volution  is  obviously  in 
the  extreme  gerontic  stage,  since  the  line  of  involution  has  retreated  consid- 
erably from  the  previous  normal  line  of  involution,  beginning  its  departure 
on  the  first  quarter  and  thus  greatly  enlarging  the  diameter  of  the  umbilical 
opening.  The  diameter  of  widest  part  is  40  mm.  without  the  shell;  with 
the  shell  it  was  8  mm.  less,  whereas  that  of  the  opening  in-  next  inner 
volution  was  only  10  mm.  with  the  shell  on.  The  oldest  sutures  were 
closer  together,  and,  like  the  decrease  of  involution,  indicated  that  the 
specimen  was  outgrown ;  but  these  did  not  show  the  extreme  degeneration 
sometimes  found  at  the  end  of  the  parageroutic  substage.  The  sutures  on 
last  half  of  the  exposed  volution  were  not  in  good  condition  and  those 
described  below  were  about  the  middle  of  the  volution,  or  in  what  I  took  to 
be  the  metagerontic  substage.  The  sutures  were  at  this  time  separated  by 
a  good  interval,  the  first  overlapping  being  between  the  fourth  saddles  and 
the  inner  side  of  the  third  loljes.  The  next  overlapping-  was  between  the 
seventh  saddles  and  continued  thence  to  umbilicus.  The  first  lateral  saddle 
on  left  side  is  very  broad  and  of  the  trifid  type,  and  the  marginal  saddles 
elongated  and  phylliform  in  outline.  It  has  an  iimer  branch  which  is 
phylliform,  and  although  it  might  be  reckoned  as  the  second  lateral,  is  only 
a  marginal,  as  in  other  forms  of  this  genus.  The  corresponding  marginal 
in  novime.ricanum  is  smaller,  and  is  not  at  all  likelv  to  be  mistaken  for  a 
second  lateral  saddle. 

The  second  is  somewhat  larger  and  less  phylliform  than  this  branch  of 
the  first  lateral,  but  has  similar  characters.  The  third  is  still  longer  and 
larger  and  has  lost  more  of  its  pliylliform  aspect  through  the  development 
of  the  long  marginal  lobes.  The  fourth  saddle  is  very  long  and  large, 
rising  above  the  level  of  the  first  laterals,  and  is  deeply  cut  and 
unsymmetrically  trifid,  each  branch  being  subdivided   except  the  central 

MON    XLIV — 03 7 


98  PSEUDOCP]RATITES  OF  THE  CRETACEOUS. 

one.  The  remaining-  saddles  are  very  short,  broad,  and  more  or  less 
phylliforin.  Tlie  fifth  is  entire  with  exception  of  minute  marginals;  the 
sixth  is  trifid  without  secondary  marginals;  the  seventh  and  eighth  are 
unsymmetrically  bifid;  the  ninth  and  tenth  are  entire  and  phylliform.  The 
eleventh  saddle  passes  across  the  lines  of  involution  and  forms  the  seventh 
saddle  of  the  dorsum.  The  corresponding  saddles  on  the  right  side  ai-e 
quite  distinct  in  detail,  but  of  the  same  number  and  similar  in  general 
aspect.  However,  the  fifth  and  sixth  laterals  are  unsymmetrically  trifid 
with  secondary  marginals,  showing  that  they  were  on  the  road  to  the 
quadrifid  type,"  and  the  seventh  is  bifid.  The  remaining  saddles  are  shown 
on  the  same  side  at  an  older  stage.  The  eighth,  ninth,  and  tenth  were 
phylliform  and  entire;  the  eleventh  was  entire,  and  situated  on  the  line  of 
involution.  The  lobes  on  the  left  side  were  as  follows:  The  first  laterals 
were  merely  marginals  on  the  first  lateral  saddles,  the  first  coi-responding  to 
the  first  saddle,  as  reckoned  above,  the  second  and  third  progressively 
deeper.  The  third,  although  it  was  apparently  trifid  in  type,  was 
subdivided  by  a  very  long,  slender,  and  peculiar  marginal  saddle  coming 
from  opening  of  fifth  lateral  saddles.  The  fourth,  fifth,  sixth,  and  seventh 
laterals  were  broad  at  the  tops  and  had  pointed  small  marginals  as  in  some 
other  more  primitive  species.  The  eighth,  ninth,  and  tenth  had  more 
unequal  serrations  aud  were  narrow  at  the  tops. 

The  adult  sutures  were  exposed  on  an  inner  volution  and  exhibited,  as 
I  anticipated,  more  overlapping  than  in  the  gerontic  stage,  owing  to  the 
greater  length  and  development  of  the  second  aud  third  lateral  saddles. 
This  is  an  instructive  case  because,  as  a  rule,  the  overlapping  is  greater  in 
the  gerontic  stage  than  in  the  ephebic.  In  the  extreme  gerontic  stage, 
when  tlie  decrease  iu  length  of  the  saddles  and  lobes  is  greatest,  the 
approximation  of  sutures  causes  overlapping,  notwithstanding  this  decrease. 
But  in  a  prolonged  gerontic  stage  the  relative  decrease  in  length  of  lobes 
and  saddles  may  sometimes,  as  in  this  case,  where  septa  are  not  nuich  closer, 
cause  sutures  to  appear  wider  apart  than  in  the  ephebic  stage. 

The  adult  sutures  had  very  much  the  same  outlines  as  in  the  gerontic 
stage  described  aoove,  but  there  was  a  slight  overlapping  along  the  entire 
suture. 

"This  shows  a  variation  between  the  two  sides  that  is  interesting,  and  it  must  also  be  noted  that 
there  is  a  sUght  overlapping  on  this  side,  owing  to  the  greater  length  of  the  fifth  and  sixth  saddles. 


C01L0P0CERATID.E.  99 

There  were  three  principal  lateral  loDes  and  the  third  was  the  remnant 
of  the  primitive  lateral  lobe. 

The  doi'sal  sutures  were  seen  in  the  gerontic  stage  and  a  partly  restored 
outline  of  the  antisiphonal  is  given  in  PI.  XII,  fig.  3.  The  right  outline  and 
the  end  of  the  lobe  are  restored.  The  extreme  bifid  end  of  this  lobe  was, 
however,  seen  from  below.  The  first  dorsal  saddle  was  clearly  seen  but 
was  apparently  abraded  like  the  antisiphonal,  and  the  remaining  saddles 
were  seen,  but  not  in  such  connection  as  to  make  a  drawing  desirable. 
They  correspond  in  outlines  to  the  opposite  lobes  and  saddles  of  the  aux- 
iliary series,  being  entire  and  phylliforra  near  the  lines  of  involution  and 
trifid  near  the  first  pair  of  dorsals.  The  lobes  also  are  digitated  like  their 
opposite  companions  of  the  auxiliary  series.  There  are  six  pairs  of  saddles, 
with  a  seventh  continuous  with  the  eleventh  outer  saddles,  and  six  pairs  of 
lobes,  the  antisiphonal  making  the  thirteenth  lobe  on  the  dorsum. 

Locality:   Rit  du  Plain,  Colfax  County,  N.  Mex. 

Age:  Colorado  group.  Upper  Cretaceous. 

CoiLOPOCERAS  REQUiENiANUM  (d'(3rbigny). 

Am,m,onites  requienianiis  crOrbig^ny,  1840,  Terr.  C'l't'tace,  pi.  93. 

The  suture  given  by  d'Orbigny  has  a  large  first  lateral,  but  it  is  narrow, 
long,  and  bifid,  with  a  third  arm  on  the  external  side.  The  two  next  saddles 
liave  the  relations  common  in  this  genus,  the  second  being  hardly  distin- 
guishable as  an  independent  saddle,  narrow,  phylliforin  and  bifid,  while  the 
third,  which  is  large  enough  to  be  ranked  as  an  independent  saddle,  is 
narrow,  jjhylliform,  and  trifid.  The  auxiliary  series  has  the  broad  complex 
saddle  to  begin  with,  reckoned  in  these  descriptions  as  the  fourth  lateral, 
and  the  remaining  saddles  have  the  usual  phylliform  bases,  all  that  are 
drawn,  four  in  number,  being  bifid. 

The  outlines  approximate  more  nearly  to  those  of  the  phylloceran  group 
like  Aconeceras  nisum.     The  siphonal  saddle,  if  correctly  drawn,  is  interme 
diate  in  aspect  between  the  broad  ventrals  of  other  species  of  this  genus 
and  those   of  such  forms  as   Platylenticeras  heteropleunim,   with  narrower 
siphonals. 

Locality:  Ilchaux,  France. 

Age:  Turonian. 


100  PSELTDOCERATITES  OF  THE  CRETACEOUS. 

CoiLOPOCERAS?  GROssouvREi  n.  s|).  Hyatt. 

PL   XII.  tijr.   7. 

Sjjhcnodiseus  7V'j>i/e»/'  Groiif>ouyvQ.  lS!t3.  Ammonites  Craie  superieure,  p.  141.  tig.  59. 

The  suture  and  description  given  by  Grossouvre  of  his  French  species 
and  the  one  fig-ured  by  d'Orbigny  as  Ammonites  rrqidenianns,  ahhoug-h 
quoted  as  identical  by  him,  are  very  difiPerent.  There  are  distinctly  three 
principal  lateral  saddles  in  (irossouvre's  figure,  but  the  first  is  large,  long, 
and  trifid  instead  of  being  narrow,  long,  and  bifid;  the  second  is  really  an 
enlarged  branch  of  the  first  saddle  and  still  entire,  while  the  third  is  bifid  and 
much  larger  than  in  true  rcquieni,  according  to  d'( Jrbigny's  figure.  This 
species  may  be  one  of  the  hollow-keeled  group,  a  suggestion  that  is  further 
supported  by  the  aspect  of  the  auxiliary  saddles  and  lobes.  In  order  to  call 
attention  to  these  points  I  have  placed  a  question  after  the  generic  name. 

Locality:  Near  Tours,  France. 

Age:  Turonian. 

ACONECERAS"  n.  gen.  Hyatt. 

The  single  species  here  referred  to  this  genus  has  sutures  more  like 

those  of  Cretaceous  forms  of  Phylloceratida  than  any  others  of  this  group. 

These  are  combined  with  a  highl}'  involute  compressed  shell  having  an 

ax-like  acute  venter  like  a  species  of  Euhphoceras.     The  A-entral  saddle,  as 

figured  l)v  d'iJrbigny,  is  broad  and  similar  to  that  of  CoUopoceras:  the  first 

lateral  and  the  other  saddles   are   deeply  divided   and  broader  tliau  in  the 

Phylloceratida  and  certainly  show  approximation  to  those  of  the  Coilopo- 

ceratida?.     I  have  therefore  referred  the  form  to  this  family,  and  it  appears 

to  strengthen  the  opinion  that  the  Coilopoceratidji?   were  derived  from  the 

Phylloceratida?. 

AcoNECERAS  NisuM  (d'Orbigny). 

PI.  XII.  %s.  J-tj. 

Aiiiinonitef:  )i,ism  d'Orbigny.  1840.  Terr.  Cretace,  pi.  55. 

This  figure  is  copied  from  d'Orbigny  because  it  gives  what  appears  to 
be  an  important  link  in  the  evidence  that  the  group  to  which  it  is  referred 
is  correctly  referred  to  the  Phylloceratida.'' 

Age:  Neocomian. 

"  Akovi;,  a  whetstone. 

''The  twc.i  pages  of  manuscript  bearing  these  notes  on  Aconeceras  were  out  of  place,  lying  at  the 
t<ip  of  one  of  the  two  ImniUes  of  manuscript,  ami  just  before  the  generic  name  i;-  the  penciled  note, 


SYSTEMATIC  DESCRIPTIONS  101 

COSMOCER^TID^. 

VASC0CERA8  Choffat." 

This  genus,  thanks  to  the  researches  of  Choffat/  can  now  perhaps  be 
assigned  to  its  jiroper  group.  In  my  chapter  on  Cephalopods  in  Zittel's 
Text-book  T  placed  it  with  a  question  mark  in  the  Acanthoceratidfe.  It  is 
apparently  a  group  of  ^ery  broad  coronate  shells  having  in  the  young 
adolescent  stage  of  some  pi-imitive  forms  (ex.  V.  subconcUiatum,  Choffat) 
three  rows  of  tubercles,  which  are  often  large  nodes  on  casts.  The  section 
is  essentially  helmet  shaped  at  this  age,  the  umbilical  zones  very  abrupt, 
iind  tlie  diameter  through  the  umbilical  shoulders  much  greater  than  that 
through  the  ventro-lateral  angles.  The  absence  of  a  keel  and  the  rounded 
ventral  zone,  interrupted  by  costte  in  some  forms,  are  characteristics  that, 
together  with  the  lateral  nodes  and  section,  are  similar  to  the  young  stages 
of  Coronitcs  and  the  discoidal  forms  of  HopUtes  that  have  similar  coronate 
young  with  a  line  of  large  nodes.  The  sutures  have  remarkably  broad  first 
lateral  saddles  and  ventral  lobes  that  are  similar  fo  those  of  some  species  of 
Heinzia  and  Metoicoceras.  These  and  the  otlier  characters  indicate  that  this 
genus  may  have  had  relations  to  typical  Pulchelliidfe  similar  to  those  that 

"Belongs  with  the   Desmoceras  group."     It  seems  probable,  therefore,  that  Professor  Hyatt  had 

changed  his  opinion  concerning  the  relationship  of  the  genus,  liut  as  he  had  arranged  figures  of  it  on 
the  plate  in  c(innecti(jn  with  figures  of  ('n'dupuceras,  it  is  thought  best  to  jprint  the  manuscript  as 
written.  The  statement  that  "the  group  *  *  *  is  correctly  referred  to  the  Phylloceratida"  is 
evidently  in  conflict  with  the  general  note  on  the  Mammitida,  which  is  made  to  include  the  Coilopo- 
ceratid;e  and  many  other  families.  I  have  not  been  able  to  determine  which  of  these  views  was  last 
held  by  Professor  Hyatt,  but  the  arrangement  of  the  manuscript  gave  the  impression  that  Aconeceraa 
was  removed  from  Coilopoceratidse  as  the  result  of  later  studies  and  that  much  of  the  evidence  for  the 
relationship  of  the  family  with  Phylloceratida  was  thus  removed. — T.  W.  S. 

"  In  the  manuscript  a  sheet  is  inserted  just  before  Vmcoceras  with  the  heading  " Cosmoceratida, " 
followed  by  "In  family  description  notice  reseral^lance  of  form  to  .-Vspidoc.  of  Jura  as  more  remote 
than  to  Chelonireran  of  the  Cretacic."  Another  memorandum  bears  pencil-sketch  copies  of 
d'Orbigny's  figures  of  AnimonHes  royerianns  (Pal.  Fr.  Terr.  Cret.,  I,  pi.  112,  figs.  3,  4)  labeled 
Chelonlcenis  royerianus,  indicating  that  he  had  probably  selected  this  species  as  the  type  of  a  new 
genus.  It  is  inferred  from  this  that  he  had  referred  Vascocerus  to  the  Cosmoceratida,  and  that  he 
intended  to  name  and  describe  a  new  family  to  include  this  genus  and  possibly  Tohjpeceras.  But  did 
he  also  intend  to  put  Coilopoceratidie,  Pulchelliid;e,  and  all  the  families  that  follow  in  the  Cosmoce- 
ratida? I  can  see  no  evidence  of  it,  except  in  the  arrangement  of  the  manuscript  and  the  absence  from 
it  of  other  super-family  names.  Certainly  no  justification  for  it  can  be  found  in  the  definition  given 
by  Professor  Hyatt  in  Zittel's  Text-book.  In  the  plates  Vascorenifs  follows  Coil(_)poceratidie,  and  I 
have  changed  the  arrangement  of  the  manuscript  sheets  as  found  so  that  the  descriptions  follow  in  the 
same  order,  Vjelieving  that  this  is  a  more  natural  order  and  that  it  represents  Professor  Hyatt's  latest 
views,  as  the  last  work  he  did  was  the  mounting  of  these  drawings  in  plates. — T.  W.  S. 

("Faune  Cret.  du  Portugal. 


102        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

highly  coronate  forms  like  Erpmnoceras  in  the  Inferior  Oolite  have  to  true 
Stepheoceras,  but  until  the  }'0ung  are  known  there  can  be  no  certainty  in 
such  conclusions. 

The  similarity  of  this  genus  to  Olcostephanus  is  very  close  indeed.  The 
costae  on  the  venter  of  that  genus  are,  however,  not  so  fold-like,  and  the  nodes 
on  the  umbilical  shoulders  are  correspondingh'  smaller  and  more  immerous. 
The  sutures  in  Olcosteplianus  are  much  more  complex  in  outline,  and  there 
are  fewer  saddles  and  lobes. 

The  coronate  form  of  the  volutions  and  deep  open  umbilici  retained  in 
some  uutuberculated  shells  have  a  certain  remote  resemblance  to  some 
foniis  of  Pachydiscns,  but,  so  far  as  I  know,  none  of  these,  nor  any  species 
of  Cretaceous  Ammonitinae,  have  volutions  so  excessively  depressed  and  so 
similar  to  the  Stepheoceratidse  of  tlie  Jura  and  some  Goniatitinas  of  the 
Carboniferous. 

The  living  chamber  is  full  three-fourths  of  a  volution  in  length.  Lat- 
eral zones  do  not  exist,  the  umbilical  zones  being  abrupt  and  the  umbilical 
shoulders  on  the  lateral  edges  of  the  venter. 

The  only  form  in  the  Cretaceous  that  is  similar  to  this  is  in  the  young 
of  Gahhioceras  hatesi  (Gabb).  This  last  has  a  similar  coronate  form  with- 
out an}-  lateral  zones  throughout  the  neanic  stage,  but  the  sutures  show 
this  to  belong  to  a  different  suborder,  the  Leptocampyli,  with  which  it  also 
agrees  in  the  aspect  of  the  shell  and  the  characters  of  the  adults. 

The  sutvires  have  very  peculiar  broad,  short  ventral  lobes  and  first 
lateral  lobes.  There  is  but  one  broad  principal  lateral  saddle,  with  coarse 
marginal  saddles;  the  lobes  and  saddles  are  aramonitic — that  is,  completely 
margined  bv  small  lobes  and  saddles.  "White's  figure  has  the  sutures  very 
im})erfect  and  much  worn  away,  but  shows  the  orad  trend  of  the  auxiliaries. 
It  is  also  defective  in  regard  to  the  first  auxiliary  saddle.  This  is  a  well- 
defined  and  very  broad  saddle,  smaller  than  the  first  lateral,  but  otherwise 
resembling  it.  The  sutures  are  considerably  worn  away  in  the  specimen 
figured,  but  the  preservation  is  better  than  in  White's  fossil.  The  differences 
in  the  sutures  and  form  from  its  assumed  congeneric  associates  in  the  Pul- 
chellida?  can  be  accounted  for  if  it  is  assumed  that  this  genus  is  in  its 
principal  characteristics  an  arrested  development  of  the  coronate  form  of 
the  early  stages,  as  stated  in  the  introduction  to  this  paper. 


COSMOCERATIDA  103 

Vascoceras  hartti  (Hyatt) 

Fl.  XIV,  %.  16. 

Cei'atite^  hai'ttii  Hyatt,  1870,  Geol.  and  Phys.  Geog.  Brazil,  p.  386. 
Bnchiceras  harttii  Hyatt,  1875,  Proe.  Boston  Soc.  Nat.  Hist.,  Vol.  XVII,  p.  37o. 
Ammonites  harttii  White,  1888,  Arch.  Mus.  Nac.  Brazil,  Vol.  VII,  pi.  1!». 
Vascoceras?  hartti!  Choffat,  1898,  Faune  Cret.  du  Port..  Vol.  I,  2d  series,  pi.  13. 

This  fine  fossil  was  received  from  Prof.  J.  C.  Brauner,  and  was  collected 
by  him  not  far  from  the  locality  of  White's  fossil  of  the  same  species.  It  is 
a  cast,  the  diameter  of  the  whole  is  175  mm.,  the  transverse  diameter  of  the 
last  volution  is  124  mm.  The  form  and  general  aspect  is  about  the  same 
as  in  White's  figure;  living  chamber  of  the  same  length — three-fourths  of  a 
volution — and  also  other  external  characters  and  sutures  are  as  described  in 
remarks  upon  the  genus;  the  inner  volutions  could  not  be  exposed.  There 
is  not  the  slightest  fragment  of  shell  upon  tliis  cast,  but  there  are  the 
remains  of  the  cemented  valves  of  two  or  three  ostreans.  With  reference  to 
these  I  again  reiterate  the  opinions  expressed  with  reference  to  Hartt's  and 
White's  specimens.  This  cast  must,  like  these,  have  been  a  fossil  at  the 
time  the  ostreans  were  building  their  sliells,  since  their  valves  are  attached 
to  the  surface  of  the  cast  and  fit  into  the  irregularities  produced  by  abrasion 
before  they  began  to  gi-ow  on  its  exposed  surface.  It  was  not  a  member  of 
the  fauna  in  which  they  were  found,  but  came  from  some  earlier  strata. 

Locality:   Province  Sergipe,  Brazil. 

Age:  Cenomauian? 

TOLYPECERAS"  n.  gen.  Hj-att. 

The  curious  species  upon  which  this  is  founded,  Tolypeceras  (Anim.') 
marcousanum,  described  and  figured  by  Pictet  and  Campiche  in  their  Ter- 
rains Cretaces  de  St.  Croix,  is  represented  in  the  collections  of  Museum  of 
Comparative  Zoology  by  a  fragment  collected  by  Jules  Marcou,  near 
Nozervy,  in  Switzerland.  This  is,  however,  sufficient  to  enable  me  to  see 
that  the  sutures  of  a  somewhat  younger  stage  than  those  figured  by  Pictet 
and  Campiche  are  of  the  same  t)-pe  as  those  of  Lenticeras,  but  with  shorter 
marginals.  The  first  lateral  saddle  is  broad  and  solid  and  the  other  saddles 
are  also  broad  and  not  deeply  cut  into.     The  outer  volution  is  22  mm.  in 

"  ToXincr/,  a  lump. 


104  FSFATDOCERATITES  OF  THE  CRETACEOUS. 

diameter  through  the  uiesal  phiiu*  ami  20  mm.  at  the  broadest  part  between 
the  uode.s.  The  next  youngest  volution  is  9  mm.  in  ventrodorsal  diameter 
an<l  9  mm.  broad. 

BARROISICERAS    Gross. mvre." 

According  to  Grrossouvre's  and  Redtenbaclier's  figures  this  genus  evi- 
dently has  smooth,  comjn'essed  young,  with  a  continuous  keel.  Grossonvre 
shows  some  forms  intermediate  between  those  of  his  involute  liaherfellneri 
and  the  verv  discoidal  ones  figured  by  Redteubacher.  It  is  very  obvious 
that  these  have  no  affinities  with  Tissotia,  unless  it  ma}'  be  through  the 
similarity  of  the  young.  The  young  in  this  and  in  Tissotia  suggests  affinity 
with  the  so-called  Oxi/noticcras  of  the  Cretaceous  figured  b}'  Xeumayer. 
Ajjpareutly  the  young  figured  by  Redteubacher  is  more  involute  than  at 
later  ages. 

The  metamorphoses  seem  to  be  (1)  entire  keel,  sides  smooth,  venter 
acute,  and  form  involute;  (2)  costated  with  entire  keel;  (3)  tuberculated 
and  costated  and  keel  broken  u])  into  tubercles  by  crossing  of  -s-enter  Vjy 
costse;  (4)  continuous  keel  again.  (See  Redteubacher,  Am.  Piion.,  Abliandl- 
K.-k.  geol.  Reichsaustalt,  Vol.  V,  1873,  pi.  23,  rig.  3  b,  d.) 

This  group,  so  fullv  described  by  Grossouvre,  contains  an  excellent 
series  of  forms  which  he  largely  includes  under  the  single  name  of  B.  haber- 
fellneri.  According  to  the  mode  of  classification  followed  in  these  pages,  the 
great  differences  in  form  and  other  characters,  including  corresponding  difi'er- 
ences  of  development  between  his  B.  haberfellneri  var.  liarlei  and  var.  des- 
moulinsi,  indicate  distinct  species  widely  removed  from  each  other.  It 
makes  no  difterence  in  following  out  this  method  whether  these  are 
obviously  connected  by  intermediate  forms  or  not,  the  sole  criterion  being 
whether  the  species  diff"er  in  tlieir  form,  involution,  and  other  characters 
.snfficientlv  to  be  arranged  in  a  natural  series  which  can  be  shown  to  lie 
parallel  or  partly  parallel  with  other  generic  groups  about  which  there  is 
more  complete  information. 


This  genus  i.s  referred  to  ^lammitidH' in  Hyatt's  chapter  in  Zittel'.s  Text-book,  while  in  the 
original  <.'oiiy  of  the  present  manuscript,  prepared  in  1S97,  it  appears  among  the  Pulchelliidie.  The 
notes  on  the  Pulfhelliidic  then  written  are  entirely  superseded  by  the  pages  in  Professor  Hyatt's  hand- 
writing published  here,  in  which  the  family  is  much  restricted  and  does  not  contain  Barruisiceran, 
Stiiliczkaia,  Tissotia,  nor  Neolohites,  all  of  which  were  incKided  in  the  original  manuscript.  These  remarks 
on  Barroisictnis  are  inserted  in  the  revised  raanus<-ript  just  Ijefore  I'ulchellidic. — T.  W.  S. 


MANTELLICERATIDA.  105 

Barroisiceras   desmoulinsi  Grossouvre. 

Barrols/'ceras  hafxrfeUiur!  var.  (hsmmib'nsi  Grossouvre,  1893,  Ammonites  Craie 
superieure,  pi.  2,  tig.  fi. 

A  verv  stout  form,  with  huge  nodes  and  having  the  continuous  keel 
until  a  later  stage. 

Locality:  Near  Perigueux  (Dordogne). 
Age:  Coniacian. 

Barroisiceras  haueri  n.  sp.  Hyatt. 

Bai^omceras  haierfellnet-i  var.  Grossouvre,  ISKS.  Ammonites  Craie  superieure, 
pi.  -2,  tig.  1  only. 

This  is  more  compressed  than  B.  desmouUnsi,  the  nodes  are  smaller  and 
more  numerous  at  the  same  age,  and  the  keel  is  broken  up  into  tubercles. 

LocaliU):  Same  as  above. 

Age:  Same  as  above. 

:SI^4l^  TELLICER-A.TID^. 

MANTELLICERATIDA. 

This  group  was  described  in  Zittel's  Text-book,  Cephalopoda,  page 
587,  as  the  Pedioceratida?,  and  included  only  the  genera  Pedioceras,  Douvil- 
leiceras,  Steuroceras  {OdontoceraH)  Cossmann,  and  Diadochoceras.  Of  these, 
Steuroceras  should  be  removed  to  the  Hoplitida?.  In  the  young,  or 
throughout  life  in  primitive  forms,  there  is  close  parallelism  with  Phri- 
codoceras  and  other  discoidal  tuberculated  forms  of  the  Cosmoceratidse,  but 
in  later  stages  the  large  single  or  imperfectly  bifurcated  costae  cross  the 
venter.  All  traces  of  tubercles  may  be  lost  at  this  or  a  later  age  in  some 
forms,  but  in  most  species  there  are  at  least  two  rows,  one  on  each  of  the 
veutro-lateral  angles.  There  is  never  at  any  stage  a  row  of  median  ventran 
tubercles  nor  a  keel,"  nor  are  the  ventral  costae  ever  cut  through  by  a 
narrow  ventral  channel,  as  in  Hoplitidae. 

«  Acomjmjcerdu  appears  to  be  an  exception  in  the  figure  given  by  Schliiter,  but  that  author  distinctly 
states  that  no  true  keel  is  formed. 


106  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

METASIGALOCERAS  u.  geu.  Hyatt. 

The  type  of  this  genus,  Metasigaloceras  rusticum  (Sow.),  has  been 
figured  by  several  authors."  All  of  these  figures,  including  Sowerby's, 
show  a  foi-m  in  section  like  that  of  Sigalnceras  tayJori  and  two  rows  of  large 
tubercles.  These  are,  however,  not  truncated  on  the  casts  as  in  that  genus, 
but  are  apparently  hollow  spines  arranged  in  two  outer  lines.  There  is  no 
inner  line  of  tubercles.  There  are  the  same  number  of  lobes  and  saddles 
on  the  sides  as  in  Sigaloceras,  viz.,  three  broad  and  rather  deep,  solid 
saddles  with  corresponding  large  lobes.  The  sutures,  as  figured  by  Sharpe, 
are  sufficiently  similar  to  those  of  other  genera  in  the  family  Mantelli- 
ceratidre  to  show  that  it  can  readily  be  placed  in  this  group.  The  first 
lateral  saddles  have  three  long  branches,  the  second  lateral  is  rather  narrow 
and,  although  well  divided,  is  club  shaped,  and  the  third  is  broad  and 
deeply  bifid.  This  outline  is  more  like  that  of  DouvUleiceras  than  any  other 
genus.  The  dorsal  sutures  could  not  be  compared.  The  alternating  costaj 
are  tuberculated  on  the  venter  of  Pseudaspidoceras  and  smooth  in  Sigaloceras. 
The  general  resemblances  to  Aspidoceras  are  apparently  close,  but  as  this 
genus  has  no  inner  line  of  tubercles  and  perhaps  no  strongly  developed 
lateral  costations  at  any  stage,  the  comparison  fails.  It  is  obviously  a 
more  primitive  form  than  that  of  Pseudaspidoceras  or  Diadochoceras. 

PSEUDASPIDOCERAS  n.  gen.  Hyatt. 

This  o-enus  is  instituted  for  some  Indian  fossils  which  in  the  adult  forms 
and  ornaments  of  some  species  show  close  parallels  with  Jurassic  Aspido- 
ceratidfe,  but  the  development  and  sutures  place  them  in  the  saine  family 
with  Diadochoceras.  Their  forms  are  discoidal  with  quadrate  volutions, 
broad  concave  venters,  flat  lateral  zones  or  sides,  prominent  umbilical 
shoulders,  and  distinct  convex,  smooth  umbilical  zones.  The  costfe  are 
wide  apart,  cross  the  venter  and  have  two  ventral  and  at  least  four  lateral 
rows  of  tubercles,  two  on  either  side.  The  young  liave  in  the  type  form 
Pseudaspidoceras  footeanum  (Stoliczka),''  stage  similar  to  that  o{  Diadochoceras 
nodosocostatuni  with,  however,  more  prominent  alternating  costw  and  more 
quadragonal  form  of  whorl. 


0  Amm.  rusticus  Sowerby,  Min.  Conch.,  p.  177;  Amm.  rusticus  d'Orbigny,  1840,  Terr.  Cr6tac^, 
pi.  Ill;  Amm.  rusticua  Sharpe,  1856,  Fo8s.  Moll,  of  Chalk  of  England,  pi.  20. 
''Foss.  Ceph.  Cret.  Southern  India,  pi.  52. 


MANTELLICERATID.E.  107 

Other  species  of  this  genus  are  as  follows:  Psetidaspidoceras  (Amm.) 
conciliatum,  mmliffi,  and  perhaps  crassitesta  Stoliczka;"  also  Pseudasp. 
(Amm.)  euomphalum  Sharpe,"  and  decidmm,  equal  Amm.  rotoniagensis 
d'Orbigny.'  There  is  also  a  stouter  species  from  the  same  locality  as  the 
last,  Rouen,  which  has  the  ventral  tubercles  in  close  approximation  and  a 
much  more  aspidoceran  aspect  than  in  the  usual  form.  This  is  Pseudasp. 
schliiteri  n.  sp.  Hyatt  {Amm.  rotomagensis  Schlilter).'' 

The  fact  that  this  species  and  MetacantJioplites  rJiotomac/ensis  (Defrance) 
which  has  a  line  of  median  ventran  tubercles  and  a  distinct  mode  of  devel- 
opment, have  been  so  often  pubhshed  under  the  same  specific  name  is  very 
interesting.  It  shows  how  close  is  the  parallelism  of  form  between  two 
widely  separated  genera,  one  in  the  gi'oup  Cosmoceratida  and  the  other  in 

the  Mammitida. 

DIADOCHOCERAS   Hyatt' 

The  young  of  this  genus,  first  cited  hi  Zittel's  Text-book,  page  587,  has 
in  its  youngest  stages  a  more  cyhndrical  volution  and  more  discoidal  form 
and  slower  growth  than  in  Douvilleiceras.     The  paranepionic  stage  has  a 
coronate  form  with  large  tubercles  and  smooth   sides,  as  seen  from   the 
umbilical  aspect.     At  this  stage  the  venter  could  not  be  seen.     Later  lateral 
costa?   appear  and  a  line  of  very  small  tubercles  at  their  inner  ends.     In 
the  neanic  stage  there  are  ventral  tubercles  situated  on  the  larger  costae 
and  a  broad  depression  occurs  between  them  on  the  continuous  costae  that 
cross  the  venter.     This  depression  is  not  at  first  present  in  the  intermediate 
untuberculated  costse,  which  are  continuous  laterally  and  ventrally.     Later 
in  the   ephebic  stage  the   intermediate   costte  disappear  on  the  sides  but 
remain  on  the  venter  and  become  dichotomous  from  the  lateral  row  of 
tubercles   of  the  larger   costations.     This  may  be  a  matter  of  individual 
variation  or  it  may  be  characteristic  of  diff"erent  species,  since  in  d'Orbigny's 
figure  (Terrain  Cretace,  pi.  75)  it  is  not  present  in  the  adult,  and  two  speci- 
mens that  I  have  handled  of  the  type  species,  Diad.  nodosocostatum  d'Orb., 
differ,  the  costs;  remaining  single  in  one  and  becoming  dichotomous  in  the 
other.     There  is  also  a  third  row  of  tubercles  developed  in  this  genus  on 
the  umbilical  shoulders  that  is  not  present  in  Douvilleiceras  until  a  later  age, 
when  the  associated  characters  are  quite  distinct. 

«FoBS.  Ceph.  Cret.  Southern  India,  pis.  50-52.  dPateontogr.,  Vol.  XXI,  pi.  6. 

bFoss.  Moll,  of  Chalk  of  England,  pi.  13.  Mid5o;fos,  a  successor. 

«Terr.  Cretace,  pi.  106. 


108  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

PEL)I0CERA8  Gerhardt 

Type  Ped.  cundinaniarcce,  Gerhardt  Kreidef(_)rmation  in  Columbien,  etc. 
Neues  Jahrb.  fur  Min.,  Geol.,  und  Pal.,  Beil.-Bd.  11,  1897-98,  p.  172,  pi.  4, 
fig-.  7.  Age  Aptiau.  A  stout,  quadragonnl,  very  discoidal  shell,  with  two 
lines  of  outer  tubercles  and  one  on  the  umbilical  shoulders,  all  very  slight, 
costae  linear,  l)ut  prominent  on  the  sides  and  crossing  the  venter,  which 
is  broad  and  concave.  The  dorsal  side  Ijarely  covers  the  outer  line  of 
tubercles.     No  sutures  given.     Includes  caqiiesensis  and  ubaquensis  Karst. 

D0UVILLEICERA8  Grossouvre. 

The  type  of  this  genus  is  the  fossil  figured  first  by  Walch  in  the 
Naturforscher,  Vol.  1, 1774,  p.  1 96,  pi.  2,  fig.  3.  This  wan  cited  by  Schlotheim 
in  his  Beitrage  zur  Naturgeschichte  der  Versteinerungen  in  Taschenbuch  fiir 
Mineralogie,  Jahr.  7,  I,  p.  1 11,  as  the  type  of  Amm.  luammUlatus.  The  figure 
given  by  Walch  seems  to  apply  to  the  young  of  the  form  usuall}'  cited  by 
authors  as  mammillaris  and  figured  by  d'Orbigny  under  this  revised  name. 
Mammillaris  is  cited  by  Grossouvre,  without  an  authority  after  the  name, 
as  the  ty;^e  of  his  genus  Douvilleiceras  in  his  Ammonites  de  la  Craie 
Superieure,  page  26,  and  the  suture  alone  is  given  ou  page  23. 

The  young  of  the  shells  in  the  genus  have  after  the  smooth  nepionic 
stage  highly  coronate  depressed  volutions  with  broad  smooth  venter  and 
a  line  of  spines  on  the  ventro-lateral  angles.  These  are  at  this  time 
coincident  with  the  umbilical  shoulders,  the  true  sides  of  lateral  zones  being 
of  later  age.  The  umbilical  zones  at  this  time  are  broad  and  smooth  and 
convex,  reaching  from  tlie  tubercles  to  the  lines  of  involution.  Faint  costse 
are  developed  from  tlie  tubercles  in  both  directions,  completely  crossing 
the  venter,  and  shorter  ones  on  the  sides.  They  appear  also  to  be  dich- 
otomous  at  tlie  tubercles.  Later  these  large  tubercles  separate  more  widely 
and  intermediate  costse  begin  to  appear,  apparently  through  arrested  devel- 
opment of  some  of  the  tuberculated  costie  already  existing.  These  have  the 
same  form  and  tubercles,  but  are  less  prominent  than  those  on  either  side 
of  them,  and  sometimes  this  is  carried  to  the  extent  of  suppressing  entirely 
the  alternate  pairs  of  tubercles.  During  this  stage  the  lines  of  ventral 
tubercles  appear,  and  those  may  be,  but  are  not  always,  smaller  on  the 
alternating  costse.  Subsequently  at  some  stage  the  smaller  costse  and 
tubercles  become  of  equal  size  with  the  others.  The  stage  with  four  lines 
of  tubercles  niav  ])ersist  until  the  shell  is  one-half  to  five-eighths  of  an  inch 


MANTELLICERATID.E.  K'9 

in  diameter,  but  usually  auother  line  of  minute  tubercles  appears  on  what 
are  to  become  the   umbilical   shoulders,   and  lateral   costa?  and  a   lateral 
zone  begin  to  appear.     This  occurs  before  or  contemporaneously  with  the 
appearance  of  another  line  of  tuliercles  on  the  ventral  costa^  close  to  the 
already  existing  ventral  lines.     In  the  next  stage  a  third  line  appears  on 
the  venter  next  to  the  last  developed,  and  usually  nearer  to  them  than  to 
the  ventro-lateral  line  of  primitive  tubercles.     At  or  about  the  same  time 
still  another  line  of  tubercles  appears  on  the  lateral  costa^  midway  between 
the  two  lateral  lines.     This  stage  of  twelve  tubercles  is  succeeded  by  a 
fourteen-tuberculated  stage,   and  in  some  cases  by  a  sixteen-tuberculated 
stao-e,  througli  the  generation  of  additional  lines  of  tubercles  on  the  venter. 
DuHng  these  later  stages  the  form  of  the  volution  changes,  losing  entirely 
its  coronate   aspect.     The  venter   becomes   more   and   more  elevated  and 
rounded,  the  costs-  more  jjromineut,  and  the  tubercles  are  apt  to  become 
more  and  more  equal  in  size,  so  that  eventually  in  some  species  it  is  diffi- 
cult to  pick  out  the  primitive  lateral  tubercles.     The  stage  of  neanic  age, 
in  which  there  are  six  lines  of  prominent  spines,  is  exactly  similar  to  the 
young  of  Pseudaspidoceras  footeunum  as  figured  by  Stoliczka  in  his  Fossil 
Cephalopods  of  the  Cretaceous  Rocks  of  Southern  India  (pi.  52). 
This  aenus  includes  the  si)ecies  described  below. 

DOUVILLEICERAS    MAMMILLARE  (d'OrbigUy). 

Ammonites  iiiammillaris  d'Orljigiiy  (pars). 

Assuming  that  the  young  of  rVUrbigny's  species  on  pi.  72  represents 
the  mammillatus  of  Schlotheim,  it  is  evident  frcm  the  collections  in  the 
Museum  of  Comparative  Zoology  that  his  supposed  mammillaris  given  on 
pi.  73  is  a  distinct  species.  The  young  have  the  same  crowded  costaj  and 
aspect  of  this  species  only  throughout  the  neanic  stage.  In  this  species 
this  crowded  condition  of  the  costs?  and  the  development  of  additional 
rows  of  crest-like  tubercles  on  the  venter  seem  to  continue  indefinitely. 
In  some  specimens  that  can  hardly  be  considered  as  anything  more  than 
sporadic  varieties,  there  are  one  or  two  additional  lines  of  tu})ercles  gen- 
erated within  the  ventral  channel,  and  in  our  shell  a  line  of  faint  tubercles 
finally  appear  in  the  middle  of  this  channel,  thus  imitating  transiently  the 
ornamentation  of  a  distinct  family,  viz,  the  Mammitida?. 

Locality:  Cherbourg,  St.  Croix,  etc. 

Age:   Albian. 


no        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

DoUVILLEICEKAS    ORBIGNYI  11.  sp.  Hyatt. 

Ammonites  mammillaris  d'Orbigny  (pars),  1840,  Terr.  Cretace,  pi.  73  (not  pi.  72). 

Through  the  neaiiic.  stage  thi.s  species  is  not  separable  from  mammil- 
lare  except  by  its  sUghtly  more  discoidal  form  and  more  prominent  tuber- 
cles on  the  venter,  but  later  than  this  the  costse  separate  as  given  in 
d'Orbigny's  figure,  through  the  iiondevelopment  of  intermediate  cost«. 
This  gives  an  entirely  distinct  character  to  the  ornamentation.  One  frag- 
ment from  Cherbourg,  in  the  Koninck  collection  in  the  Museum  of  Com- 
parative Zoology,  shows  perhaps  a  third  species,  since  this  change  is  much 
more  pronounced  than  in  the  type  cited  above  and  occurs  at  an  earlier  age. 

This  genus  is  represented  in  North  America  by  T)ouv.  (Accmth.) 
spimferum  (Whiteaves),  found  in  Canada,  and  there  seem  to  be  two 
species,  the  first  described  in  Mesozoic  Fossils,  Vol.  1,  pt.  1,  pi.  4,  and  the 
second  in  the  same,  pt.  4,  pi.  35.  The  diff"erences  appear  to  lie  in  the 
costations  and  tubercles  of  the  older  stages. 

Localities:  Numerous,  western  Europe. 

Age:  Albian. 

SCHLUETERICERAS  n.  gen.  Hyatt. 

This  group  has  in  its  type  species  Schluetericeras  nodosoides,  described 
and  figured  in  Schliiter's  Cephalopoden  der  oberen  deutscheii  Kreide  (p.  18, 
pi.  8,  figs.  1-4)  a  neanic  stage  with  compressed,  flat-sided,  moderately 
involute  shell  that  resembles  the  neanic  shells  of  Meloicoceras  and  Mantelli- 
ceras  in  aspect  and  in  the  possession  of  six  rows  of  tubercles  and  a  concave, 
keelless  venter.  In  the  next  stage,  however,  the  ventral  lines  of  tubercles 
are  lost,  thus  reducing  the  shell  to  a  quadri-tuberculate  stage  and  much 
larger  and  longer  nodes  and  more  prominent  single  lateral  costal  are 
developed,  while  at  the  same  time  the  venter  becomes  flatter.  This  is  a 
degenerative,  obviously  gerontic  ciiange,  but  it  is  so  distinct  from  the 
similar  stages  of  other  genera  that  it  is  quite '  suflicient  to  characterize  the 
group.     It  is  from  the  Lower  Turonian  according  to  Schliiter. 

Other  species  of  this  genus  are  as  follows:  Schluetericeras  vielbanci  of 
the  Turonian,  described  and  figured  by  d'Orbigu}^  in  Terrain  Cr^tacd 
(pi.  108)  as.  woolf/ari,  but  changed  in  his  Prodrome  (Pt.  II,  p.  189)  to  this 


MANTELLICERATID.E.  Ill 

name.  The  reference  to  this  genus  accounts  for  the  retention  ot  two  lines 
of  obsolescent  tubercles  on  the  flat  venter  between  the  lai-ge  ventro-lateral 
spines.  Scliluetericeras  laubei,  described  by  Laube  and  Bruder  in  Aramoni- 
ten  der  Bohraischen  Kreide"  as  nodosoides  of  Schliiter,  and  Schli(etericeras 
michehhense  occur  in  the  Upper  Turonian  and  are  distinct  in  their  forms, 
especially  their  large  nodes  and  costae,  and  in  their  tendency  to  form  detinite 
channels  on  the  venter,  from  either  vielbanci  or  nodosoides 

SHARPEICERAS  n.  gen.  Hyatt. 

This  genus  in  its  full-grown  condition  has  veiy  nearly  the  same  form 
and  characteristics  as  the  neanic  stage  of  Mantellicercis  niantelli.  There  are 
eight  lines  of  tubercles  and  the  volution  is  compressed  quadrate  in  section. 
The  costa?,  are  however,  more  evenly  developed  and  do  not  bifurcate  in  the 
figures  given  ])y  Sharpe.  These  characters  are  so  marked  and  it  is  so 
plainly  a  phyloueanic  form  that  it  can  not  be  placed  in  the  same  genus 
with  Mantelliceras.  Its  characters  in  old  age  are  unknown,  but  in  the 
young,  according  to  Sharpe,  the  cost*  are  dichotomous  from  tlie  line  of 
tubercles  on  the  umbilical  shoulders. 

Type  is  Sharpeiceras  lutidavium  (Sharj)e),  figured  on  pi.  1-i  of  his 
Fossil  Mollusca  of  the  Chalk  of  England  (Pt.  I,  pi.  14). 

Sharp,  schlueteri  n.  sp.  Hyatt,  described  as  Ammonites  laticlavius  bv 
Schliiter  in  Cephalopoden  der  oberen  deutschen  Kreide  *  is  a  Cenomanian 
species  with  less  rapidly  growing  and  less  compressed  volutions  than  in  the 
English  shell.  Sharp,  inconstans  (Schliiter)  is  a  more  involute  species  of 
the  same  genus,  having  in  its  old  age,  if  correctly  defined  by  Schliiter,  a 
volution  precisely  similar  to  that  of  the  genus  Acompsoceras.  All  of  these 
belong  to  the  Cenomanian 

ACOMPSOCERAS'^  n.  gen.  Hyatt. 

The  type  of  this  genus,  Acompsoceras  bochumense,  was  described  by 
Schliiter  in  his  Cephalopoden  der  oberen  deutschen  Kreide,"*  from  the 
Cenomanian.  In  the  adult  stage,  as  described  and  figured,  it  has  large 
fold-like  costse  on  the  lateral  zones,  with  two  rows  of  tubercles,  one  on  the 
edges  of  a  flattened  venter  and  the  other  on  the  dorsal  shoulders.     These 


aPalfEontogr.,  Vol.  XXXIII,  1887,  p.  229,  pi.  25.  <■  !4«-o//^o?,  unadorned. 

ftPateontogr.,  Vol.  XXI,  pi.  7.  ''Palseontogr.,  Vol.  XXI,  pis.  1,  2. 


112        PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

are  exactly  like  those  of  I'alcheUia.  In  the  aspect  of  these  ornaments  and 
in  the  convex  venter  with  its  nascent  keel  or  raised  line  there  is  also  a  close 
resemblance  to  Roemeroceras  and  even  to  Buehiceras.  But  Schliiter  dis- 
tinctly states  that  this  is  not  a  keel  "und  der  Sipho  driickt  die  Mittellinie 
des  Bauches  etwas  in  die  Holie,  ohne  dass  jedoch  ein  eigentlicher  Kiel 
entstande."  In  old  age  the  sides  become  smooth  and  the  venter  rounded, 
and  all  traces  of  tubercles  and  costse  are  lost.  Tlie  sutures  have  a  decided 
similarity  to  those  of  Sharpeiceras  inconstans,  and,  as  stated  in  noticing  that 
species,  the  older  stages  of  tliis  species  are  similar  to  those  of  bochumense, 
while  the  younger  ones,  including  the  ephebic  stage,  have  the  character- 
istics of  Sharpeiceras.  This  implies  genetic  connection  witli  that  genus, 
and  if  confirmed  by  further  observation,  settles  the  origin  of  the  group. 
The  voung  are  not  known,  and  until  these  are  known  it  is,  of  course,  ques- 
tionable whether  the  affinities  for  Sharpeiceras  are  as  close  as  is  assumed 
here. 

Acompsoceras  essendense  (Schliiter),  described  in  the  work  quoted 
above,  and  also  from  the  ('enoinanian,  is  another  species  of  the  same  genus. 

Acompsoceras  renevieri  (Sharpe). 

Ammonite.'i  renevieri  Sharpe.  1856.  Foss.  Moll,  of  Chalk  of  Englaiul,  pi.  itO. 

This  species  is  from  the  Grray  Chalk  (Cenomanian)  of  England  and 
has  been  refen-ed  to  as  similar  to  essendense.  It  is  a  more  compressed  form 
than  either  Acompsoceras  bochumense  or  essendense,  but  has  a  nascent  keel 
and  two  rows  of  large  tubercles,  one  on  the  ventral  edge  and  the  other  on 
the  umbilical  shoulders  which  are  similar.  The  tubei-cles  are  connected  by 
broad  fold-like  costa?  with  intermediate  shorter  costations  that  sometimes 
bifurcate  from  the  longer  ones. 

The  sutures  have  a  large,  deep,  and  rather  narrow  ventral  lobe  divided 
by  an  entire  siphonal  saddle.  The  first  lateral  saddle  has  three  large 
marginals,  the  first  lateral  lobe  is  long,  rather  narrow,  and  bifid.  There  are 
but  three  lateral  saddles,  the  innermost  of  good  size  and  bifid.  If  this 
suture  is  coiTCctly  drawn  by  Sharpie,  it  is  more  like  that  of  Barrolsiceras  as 
figured  by  Grossouvre  than  that  of  Acompsoceras.  But  until  the  young  is 
known,  the  generic  name  should  be  considered  uncertain.  The  sutures  also 
are  not  unlike  those  of  some  species  of  the  keeled  and  tuberculated  forms 
like  coupei,  etc 


MANTELLICERATID.E.  113 

MANTELLICERAS  n.  gen.  Hyatt. 

At  first  sight  the  type  of  thits  group,  Mnnfelliceras  mantelU,  appears  to 
belong  to  the  same  genus  as  Metokoceras,  but  a  shght  examination  of  the 
development  shows  them  to  be  generieally  separable.  The  tuberculated 
young  ManteUiceras  approximates  to  the  type  of  development  exhibited  by 
BouviUeicerm,  and  is  a  compressed  tachygenie  form  of  the  same  family. 
The  adult  characteristics  also  show  no  close  affinities  for  the  Pulcliellian 
group  to  which  Metokoceras  probal^ly  belongs. 

The  type  species  can  not  frequently  lie  separated  from  Calycoceras " 
naviciilaris,  owing  to  the  similarities  caused  by  the  continuity  of  the  costae 
across  the  venter  and  the  presence  of  similar  lines  of  ventral  and  lateral 
tubercles.  The  development,  however,  and  the  forms  in  well-preserved 
fossils  are  both  distinct  and  their  variations  lead  in  different  directions. 
C.  navknlaris  has  the  coronate  form  prolonged  in  its  early  stages  and  the 
costa?  prominent  on  the  venter  and  a  median  ventran  line  of  tubercles 
during-  its  neanic  stage  and  sometimes  later.  The  furrowing  of  costse  on 
the  venter  is  of  later  development,  and  if  Sharpe's  figures  and  descriptions 
in  Fossil  MoUusca  of  the  Chalk  of  England,  page  39,  pi.  18,  are  correct, 
it  is  due  to  the  disappearance  of  this  line  of  tubercles.  I  have  not  been 
able  to  get  the  young  of  this  sjiecies  for  stud}',  but  that  this  line  of  tubercles 
is  sometimes  retained  until  later  is  obvious  in  some  specimens  that  I  have 
had  in  hand. 

The  relations  of  the  young  to  those  of  Dotwillekeras  are  obvious  during 
the  stage  in  which  the  volutions  have  a  very  broad  ventral  channel,  with 
costte  crossing  the  venter  and  six  rows  of  tubercles,  and  before  the 
innermost  and  eighth  rows  arise  on  the  inner  ends  of  the  costa;.  In 
the  octotuberculate  stage  they  are  like  the  full-grown  form  of  Sliarpekents 
kitidavium.  The  shell  of  M.  Diaiitelli  is  at  that  time,  a  middle  neanic 
substage,  very  closely  similar  to  DouviUeiceras  indmmUkttuni  in  its  sexitu- 
berculate  stage.  No  additional  lines  of  tubercles  are  added  in  tliis  genus. 
On  the  other  liand,  the  tendency  is  toward  complete  suppression  of  all 
except  the  two  ventral  rows.  These  disappear  also  in  extreme  age.  The 
sutures  are  obviously  of  the  same  type  as  in  other  genera  of  this  family  and 
are  closer  to  those  of  BouviUeiceras  than  any  other  genus. 

a  KdXvi,,  calyx.     Noted  in  Zittel's  Text-book,  Cephalopoda,  p.  589. 
MON    XLIV — 03 8 


]  14        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Mantelliceras  jiantelli  (Sowei-by). 

Ammonites  iiMnteUi  So-wevhy,  1814,  Min.  Conch.,  pi.  55. 

Ammonites  mantelll  Sharpe  (pars.),  1S56,  Foss.  Moll,  of  Chalk  of  England,  pi.  18, 

figs.  6,  7  (not  fig.  4). 
Aiiimoniteii  manteUi  Schliiter,  1872,  Palfeontogr. ,  Vol.  XXI.  pi.  5  (not  pi.  6). 

The  compressed  form,  with  broad  veuter,  and  presenting  clearly  three 
facets,  with  four  rows  of  tubercles,  more  or  less  well  defined,  is  obviously 
the  shell  that  more  nearly  than  others  answers  to  Sowerby's  description  and 
figures.  This  is  obviously  the  form  that  in  the  young  is  the  least  involute 
and  has  the  most  decidedly  quadragonal  volutions,  becoming  compressed  in 
later  stages.     This  is  the  var.  (a)  of  8harpe,  as  quoted  above. 

Mantelliceras  couloni  (d'Orbigny). 

AmiiKmites  mantelll  d'Orbigny,  1840,  Terr.  Cretace,  pi.  104  (not  pi.  103). 
Ammonites  couloni  d'Orbigny,  1850,  Prodrome  de  Paleontologie,  II,  p.  147. 
Ammonites  mantelll  Sharpe,  1856,  Foss.  Moll,  of  Chalk  of  England,  pi.  18,  fig.  4  (not 

figs.  6,  7). 
Ammonites  mantelli  Schliiter,  1872,  Palaeontogr. ,  Vol.  XXI,  pi.  ti  (not  pi.  5). 

This  is  a  highly  compressed  shell,  separable  even  in  the  neanic  stage 
from  mantelli.  The  young  are  mucli  more  compressed  than  in  manteUi,  sides 
flatter,  and  the  form  resembling  that  of  the  full  grown  of  that  species  when 
the  shell  is  not  over  three-fourths  of  an  inch,  or  about  18  mm.,  in  diameter. 
The  tubercles  are  present,  but  much  less  prominent  in  the  young  than  in 
mantelli  at  the  same  age. 

Mantelliceras  picteti  n.  sp.  Hyatt. 
Ammonites  mantelli  Pictet  et  Campiche,  1859,  Terr.  Cret.  de  St.  Croix,  p.  200,  pi.  26. 
The  neanic  stage,  with  its  more  compressed  form,  but  otherwise  like 
the  young  of  manteUi,  and  all  stages  are  finely  illustrated  by  the  authors 
quoted  above.  The  volutions  are  more  compressed  than  in  mauteUi  and 
somewhat  less  involute  in  all  stages  later  than  the  neanic,  and  the  venter 
narrower.  The  octotubereulate  stage  is  more  prolonged  and  the  umbilicus 
wider  than  in  M.  couloni.  In  extreme  old  age  the  tubercles  are  all  lost  and 
costfe  are  prominent  where  they  cross  the  narrow  rounded  venter.  There 
are  a  number  of  this  species  and  casts  of  some  of  Pictet's  originals  in  the 
Museum  of  Comparative  Zoology. 


MET01C0CERAT1D.E.  115 

Locality:  St  Croix. 
Age:  Cenomauian. 

Mantellicekas  vicinale  (Stoliczka). 
Ammonites  vicinaUs  Stoliczka,  1865,  Foss.  Ceph.  Cret.  Southern  India,  pi.  U. 
Locality:  India. 

Mantelliceras  ushas  (Stoliczka). 

Aiiniionites  ushus  Stoliczka,  1865,  op.  cit.,  pi.  51. 
Locality:  India. 

Mantelliceras  indianense  Hyatt. 

Aiiimonttes  inantelU  Stoliczka,  1865,  op.  cit.,  pi.  -11,  -12. 

This  species  is  similar  to  true  manielli,  but  the  shell  retains  the  eight 
rows  of  tubercles  and  the  facetted  form  until  a  much  later  age.  It  finally 
loses  these  larval  characters  and  takes  on  the  usual  aspect,  with  only  two 
rows  of  ventral  tubercles  and  compressed  volutions.  There  are  probalily 
two  species  under  this  name.  The  type  of  this  is  fig.  1,  pi.  42,  a  more 
ornate  shell  than  any  variety  of  mantelli,  with  larger  tubercles  and  deejjer 
depressions  on  the  venter. 

Mantelliceras  domeykanum  (Bayle  and  Coquaud). 

Ammonites  (hnutyhmu.s  Bayle  and  Coquand,  Fo8s.   secondaires  rec.   dau>i  le  Chili, 
etc.,  p.  10,  pi.  2,  ligsi.  2-5. 

Retains  the  tuberculate  stage  until  quite  large,  and  in  the  full-grown 
shell,  which  is  of  great  size,  the  last  volution  being  80  and  90  mm.  in 
diameter  in  one  specimen,  there  are  still  six  lines  of  well-developed 
tubercles  and  the  subquadrate  form  of  the  volution  is  but  little  modified 
This  is  by  far  the  most  primitive  form  of  this  group. 

METOICOCERATID2E    Hyatt. 

This  family  is  necessarily  instituted  for  a  peculiar  group  of  species 
whose  development  does  not  admit  them  within  the  pale  of  either  Heinzidse 
or  Pulchellid»,  but  whose  later  stages  show  that  they  belong  in  the  same 
group  with  the  latter.  The  family  and  generic  and  to  some  extent  specific 
characters  are  necessarily  mingled  in  the  following  descriptions: 


116  PSEUDOCERATITES  OF  THE  CKETACEOUS. 

METOICOCERAS"  n.  gen.  Hyatt. 

The  young,  altliougli  distinct  from  those  of  Heimia,  enable  us  to 
connect  Heinzia  and  its  more  modified  allies  with  what  I  have  misnamed  in 
Zittel's  Text-book  the  Pedioceratidfc/'  here  corrected  to  Mantelliceratidse. 

The  tyi)e  species,  if  the  full-grown  shells  were  the  sole  evidence, 
would  necessarily  fall  into  the  same  genus  with  Heinzia  matiira  on  account 
of  the  resemblance  of  the  compressed  later  stages.  But  the  following 
description  of  the  young  shows  this  to  be  a  case  of  raorphic  equivalence 
based  on  entirely  distinct  modes  of  development. 

The  earliest  stage  observed  has  a  coronate  form  with  large  lateral 
tubercles.  Tliis  stage  is  of  short  duration  and  appears  on  what  seemed  to  be 
still  the  nepionic  stage  at  about  2  to  2.5  mm.  in  diameter.  The  venter  at 
this  time  is  liroadly  rounded  and  without  costae  on  the  cast.  Subsequently 
at  diameter  of  about  3  mm.  the  ventral  rows  of  tubercles  begin  to  appear 
upon  fine  costse  that  pass  across  the  venter  and  connect  the  rows  of  tubercles, 
and  the  costae  also  begin  to  spread  inward  on  the  sides.  The  termina- 
tions of  these  at  4  nun.  diameter  were  without  tubercles.  The  costae  are 
partially  bifurcated  at  the  outer  row  of  ventro-lateral  nodes,  but  onl)'  one 
of  each  pair  passes  across  the  venter.  The  two  rows  of  ventral  tubercles 
are  borne  upon  this  costation,  and  in  front  of  each  one  is  a  depression  or 
transverse  furrow  exactlj'  like  those  that  are  so  peculiar  and  characteristic 
of  Cheloniceras  royeriammi.  Intermediate  costae  begin  to  appear  a  little  later 
and  at  first  are  without  tubercles  and  are  single.  In  this  stage  there  is  an 
evident  modification  of  a  late  neanic  substage  of  Cheloniceras,  which  has 
similar  costa?.  but  a  more  coronate  form.  These  costa?  subsequently  form  a 
branch  of  the  dichotomous  lateral  costations  or  may  remain  single  and 
short.  Though  the  resemblance  to  Aspidoceras  is  apparent,  the  general 
form  and  aspect  at  this  age  can  be  accounted  for  as  a  parallelism  with  Psen- 
daspidoceras  of  India,  which  is  one  of  the  same  stock,  and  arises  as  the 
result  of  the  assumption  of  the  subquadrate  form  after  the  coronate  stage 
in  related  organisms.  It  is  of  course  very  likely  that  this  Aspidoceran 
aspect  may  have  some  genetic  significance,  but  the  connections  that  would 
prove  this  are  not  as  yet  clearly  made  out.  One  can  not  accept  all  of  the 
characteristics  that  appear  in  larval  forms  as  of  unquestionable  genetic 
significance.      Thev  are  safe  guides   onh-  wlien  carefully  compared   and 


"  MiroiKO';,  an  emigrant.  ^  See  MantelliceratidiP. 


METOICOCERATID.E.  117 

systematically  liandled  with  due  regard  to  the  collateral  evidences,  deduci- 
ble  from  the  later  stages  of  development  and  the  obvious  relations  of  the 
adult  and  even  senile  stages.  Thus  in  the  present  case,  wliile  the  young 
would  place  this  genus  entirely  outside  the  pale  of  the  Heinziidfe,  the 
later  neanic  and  the  ephebic  stages  and  old  age  and  sutures  show  them 
to  belong  near  that  group.  The  peculiar  elongated  erestlike  tubercles, 
the  costiie,  and  iinall}-  the  sutures  are  of  the  Pulchellian  type.  When 
these  later  stages  are  allowed  their  full  weight,  it  is  then  seen  that  the 
development  shows  Metoicoceras  to  be  the  descendant  of  some  common  form 
from  which  Carstenia  tuherculafa  and  Heinzia  provinciaUs  are  also  descended. 
It  is  also  apparent  that  this  must  have  been  either  similar  to  or  identical 
with  some  species  of  the  coronate  genus  described  here  as  Cheloniceras. 
The  coronate  young  of  Metoicoceras  are  not  reconcilable  with  the  young  of 
Heinzia  nor  any  other  form  of  this  family,  so  far  as  known.  The  develop- 
ment of  Heinzia  ditfers  in  the  suppression  of  the  coronate  stage  and  of  the 
sextuberculate  stage  and  the  appearance  of  the  approximated  lines  of  tuber- 
cles on  the  venter  of  the  Heinzian  type  by  a  tachygenic  mode  of  develop- 
ment common  in  this  group.  The  difficulty  of  reconciling  the  development 
lies  in  the  fact  that  the  outer  rows  of  tubercles  appear  later  thnn  the  ven- 
trals  and  are  not  developed,  like  those  of  Metoicoceras,  from  a  primitive  row 
preceding  the  ventrals  in  development.  This  may  be  a  case  of  what  Cope 
has  called  retardation  of  development,  but  if  this  is  so,  the  effect  is  really  to 
accelerate  the  appearance  of  the  Heinzian  characteristics  of  the  venter. 

The  sutures  of  the  entire  gi-oups  of  Cheloniceratidse  and  Mantelliceratidse 
are  of  the  same  type.  The  number  of  lobes  and  saddles  is  nmch  more 
limited  than  in  Heinziidse  or  Pulchelliida?,  both  on  the  dorsum  and  externally. 
The  outlines  also  are  excessively  complex,  with  a  certain  ragged  look  due 
to  their  long,  subdivided  marginals,  and  also  apt  to  be  asymmetrical  or  trifid 
rather  than  bihd.  There  is  also  a  noticeable  absence  of  simple  entire  sad- 
dles and  lobes  in  the  umbilical  region.  Comparison  of  the  sutures  of 
Metoicoceras  with  those  of  Heinzia  or  Pulchelliu  shows  at  once  resemblances 
that  are  quite  close  enough  to  place  swallovi  in  the  same  group  with  Heinzia, 
and  the  sutures  of  Metoicoceras  are  especially  close  to  those  of  Carstenia! 
tuhercidata.  The  development,  being  irreconcilable  with  that  of  any  form 
of  Heinziidse  or  Pulchelliidse,  shows  that  the  genus  can  not  be  placed  in 
either  of  these  families  without  confusing  the  picture  of  their  systematic 
and  genetic  relations,  so  far  as  now  known. 


118  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Metoicoceras  swalloyi  (Shumard). 
PI.  XI,  figs.  7-24;  PI.  XIII,  tigs.  1,  2;  PI.  XV.  figs.  1-4. 

Ammonites  stoallovi  Shumard,  1859,  Trans.  St.  Louis  Acad.  Sci..  Vol.  I,  p.  .591. 

So  far  as  I  have  been  able  to  see,  this  species  has  not  been  previously 
fio-ured,  but  that  described  below  as  ivhitei  has  been  the  one  selected  as  the 
typical  form  of  swallovi. 

The  following  quotation  from  Shumard's  description  shows  that  while 
he  had  in  hand  perhaps  both  of  the  species  here  described  his  remarks  seem 
to  apply  more  decidedly  to  the  one  selected  as  sivallovi  rather  than  to  its  less 
prominently  nodose  and  more  complex  companion.  Shumard  states  "dorsum 
[venter]  flattened,  transversely  ribbed,  nodose-bicarinate ;  *  *  *  umbili- 
cus deep,  exhibiting  about  one-third  of  each  of  the  inner  volutions  and  about 
as  wide  as  one-half  of  the  width  of  the  last  volution."  If  he  had  in  hand  such 
a  specimen  as  the  one  he  mentions  as  being  6  inches  in  diameter,  and  it  was 
a  representative  of  tvhitei,  this  large  umbilicus  would  be  just  about  in  this 
proportion,  but  it  would  be  inapplicable  to  an  ephebic  stage  as  a  young 
specimen  of  this  species.  If  he  had  had  a  specimen  of  M.  sivallovi,  the 
large  umbilicus  would  have  been  found  in  the  neaiiic  and  ephebic  stages  in 
about  this  proportion.  Shumard's  other  remarks  apply  also  about  equally 
well  to  either  species,  but  the  sutures,  as  described  by  him,  point  out  quite 
clearly  the  typical  form.  "Dorsal  saddle  almost  double  the  width  of  the 
superior  lateral  lobe  and  divided  into  two  unequal  branches  by  a  short 
subcorneal  auxiliary  lobe;  the  dorsal  [outer]  branch  having  three  small 
notches,  while  the  inner  one  is  rounded  and  has  usually  only  a  single  small 
notch  at  its  internal  border."  Such  simple  outhnes  as  these  occur  only  in 
the  forms  here  referred  to  as  sivallovi,  and  one  of  the  specimens  (PI.  XIII, 
fig.  2)  came  from  Grayson  County,  Tex.,  the  typical  locality  quoted  by 
Shumard. 

The  young  figured  (PI.  XI,  figs.  7-15)  and  the  sutures  (PI.  XI,  figs. 
18-23)  were  taken  from  a  specimen  found  in  a  piece  of  the  matrix  cracked 
off"  from  the  specimen  shown  in  fig.  16  and  are  quite  likely  the  young  of 
this  species,  but  it  is  probable  that  at  this  age  the  diff'erences  are  slight 
between  this  species  and  whitei.  Tlu-ee  specimens  were  obtained  from  this 
piece  of  matrix.     That  to  which  figs.  12,  13  belonged  reached  an  older 


METOICOCERATID.E.  1 1 9 

stage  than  figs.  14,  15,  and  the  last  node  near  the  umbiHcus  on  this  was 
considerabh"  hirger  than  the  preceding  nodes,  indicating  that  this  young- 
one  belonged  to  this  species.  The  breadth  of  side  at  this  age  was  about 
9  mm.,  the  transverse  diameter  about  6  mm.  The  breadth  of  the  side  at 
the  base  of  the  living  chamber,  which  was  badly  crushed  farther  on,  in 
fig.  16  is  20  mm.,  while  the  diameter  between  the  tubercles  is  16  nnu.  The 
young  volution  was  quadrate  in  form,  the  sides  parallel,  whereas  in  the 
specimen  represented  by  fig.  16,  as  may  be  seen  in  fig.  17,  the  lateral  zones 
are  highh-  inclined  and  the  venter  much  narrower  than  in  the  young.  In 
the  fossil  shown  on  PI.  XII,  fig.  2,  the  breadth  of  the  side  at  the  third  suture 
is  about  33  mm.,  the  transverse  diameter  between  the  costal  being  23  nun. 
The  outward  inclination  of  the  sides  in  this  specimen  was  not  so  great  as  in 
the  fossil  represented  by  PI.  XI,  figs.  16,  17,  even  at  the  same  stage,  and 
the  nodes  near  the  umbilicus  were  apparently  not  quite  so  prominent. 
Besides  the  marked  prominence  of  the  nodes  and  their  dichotomous  costa?, 
the  li^•ing  chamber  in  the  young  (figs.  14,  15)  is  clearly  nearl}^  three- 
fourths  of  a  volution  in  length,  while  in  the  later  stage  it  appears  to  be  in 
part  complete  and  to  be  one-half  of  a  volution  in  length.  It  is  obvious  that 
this  species  becomes  more  compressed  with  increasing  age,  and  has  a  much 
narrower  venter  and  less  transverse  diameter  in  proportion  to  the  ventro- 
dorsal than  in  the  young.  The  protoconch  has  an  arcuate  venter  (PI.  XI, 
figs.  7-10)  and  rounded  dorsum,  with  subangular  bend  as  the  outline 
approaches  the  opening  of  the  conch.  This  opening,  doubtless  once  the 
aperture  of  the  protoconch,  is  much  depressed  or  broad  transverselv  and 
continues  to  have  this  form  throughout  the  ananepionic  and  inetanepionic 
substages.  The  elevation  of  the  venter  begins  in  the  second  volution, 
fig.  10,  but  the  form  remains  smooth  and  the  sutures  goniatitic  until 
about  the  fourth  volution."  Then  nodes  begin  to  appear  on  the  ventro- 
lateral angles  and  the  venter  becomes  broader  in  consequence.  The  venter 
is  smooth  at  this  substage,  the  first  of  the  neanic  substages.  In  the  next 
substage,  about  one-half  of  a  volution  later,  fig.  14,  the  costge  become  more 
prominent  near  the  umbilici  and  wrinkles  appear  on  the  venter,  each 
accompanied  by  a  pair  of  tubercles.  In  the  next  substage,  which  was  not 
seen,  it  is  probable  that  these  ventral  costse  become  connected  with  the 
lateral  ones  and  equal  in  number  to  them,  and  nodes  appear  on  the  innei- 

0  This  was  guessed  at. 


120        PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

ends  of  the  lateral  costse  and  there  fuse  into  more  or  less  dichotonious 
forms.  This  fusion  is  not  as  complete  in  the  fossil  shown  in  fig.  16  as  it  is 
in  the  one  shown  in  PI.  XIII,  fig.  2,  at  a  later  age. 

The  sutures  seem  to  follow  about  the  same  steps  in  progress  of  devel- 
opment as  the  external  cliaracters.  Fig.  11  gives  an  enlarged  sketch  of 
(•a?cum,  which  seems  small  in  this  specimen  and  which  ojjens  into  a  large 
siphuncle,  whose  parts  could  not  be  .studied  any  further  than  is  visible  in 
the  drawing.  Although  every  eifort  was  made,  and  this  specimen  was 
remarkably  clear  and  transparent,  nothing  definite  could  be  made  out 
beyond  the  cpecum.  It  is  certain  that  the  dark  color  of  the  wall  of  this 
V)()dy  has  no  posterior  prolongation  or  prosiphonal  continuation.  The 
second  septum,  beginning  tlie  sutures  of  the  metanepionic  substage,  had 
unquestionably  a  divided  ventral  lobe,  as  given  in  fig.  10.  This  was  estab- 
lished by  many  repeated  observations.  There  were,  as  usual,  but  two 
broad  goniatitic  saddles  of  the  Tornoceran  type  on  either  side  and  one 
broad  lateral  lobe  on  each  side,  with  a  distinct  saddle  at  the  line  of  involu- 
tion. I  was  not  able  to  detect  any  depression,  such  as  I  have  prcAaously 
described  in  other  forms  as  an  embryonal  umbilicus,  occurring  at  the  begin- 
ning of  the  true  conch.  In  the  paranepionic  substage  the  suture  becomes 
distinctly  divided  on  the  sides  into  two  broad  saddles,  with  a  lateral  lobe 
and  a  lobe  at  the  line  of  involution  on  either  side,  and  during  this  substage 
the  dorsal  suture  assumes  finally  the  aspect  given  in  fig.  21.  The  sutures 
(figs.  18-20,  22)  belong  to  the  neanic  stage,  represented  in  figs.  12-15. 
They  show  the  usual  mode  of  division  common  in  Ammonoids  of  the  Jura 
and  Cretaceous,  tlie  incoming  of  auxiliarv  inflections  on  the  primitive 
second  lateral  saddle  and  the  primary  bifid  division  of  the  first  lateral 
saddle  and  first  lateral  lobe,  the  entire  aspect  of  the  siphonal  saddle  and  its 
subsequent  bifidity.  Fig.  22  of  PI.  XI  shows  the  peculiar  prolecanitean 
aspect  of  the  dorsal  inflections  before  the  end  of  the  neanic  stage,  and  illus- 
trates my  previous  statements  with  regard  to  the  retention  of  ancestral 
characters  by  these  internal  sutures.  Fig.  23  of  PI.  XI  and  fig.  1  of  PI.  XIII 
are  of  very  nearly  the  same  age,  and  give  the  beginning  of  the  ephebic 
substages.  The  latter  show  that  the  primitive  median  marginal  lobe  of  the 
primitive  dorsal  saddle  becomes  the  large  marginal  dividing  the  full-grown 
first  lateral  saddles.  This  sutui-e  also  shows  that  the  second  lateral  saddle 
has  a  trifid  termination  in  some  .specimens  of  this  species. 


METOICOCERATID.E.  121 

The  sutures  iu  the  two  specimens  here  described  as  swaUovi  are  some- 
what abraded,  liut  their  details  of  outline  are  sufficiently  well  preserved  in 
different  sutures  to  enable  one  to  see  how  much  simpler  they  are  than  in 
M.  whitei.  This  simplicity  of  the  marginals  is  not  so  great  in  some  speci- 
mens as  it  is  in  fig.  2  of  PI.  XIII,  since  in  the  suture  (PI.  XIII,  fig.  1)  the 
second  lateral  is  trifid  and  in  fig.  13  the  fourth  lateral  saddle  is  bifid.  The 
number  of  inflections  on  the  sides  appears  to  be  less  in  this  species  than  in 
tvhitei,  five  only  being  present  on  both  sides,  with  saddles  at  the  lines  of 
involution;  and  in  the  fossil  shown  in  PI  XI,  fig.  16,  there  is  the  same 
numl)er,  with  a  lobe  at  the  line  of  involution. 

Local iti/:   Grayson  County,  Tex.;   Utah. 

Affe:  Colorado  epoch. 

3Ietoicocekas  gibbosum  n.  sp.  Hyatt. 

PL  XV,  %s.  5-8. 

The  single  fossil  upon  which  this  species  is  founded  could  not  be 
placed  in  an}-  of  the  species  here  described  under  the  same  genus.  It 
has  stouter,  broader  volutions  than  any  of  these,  and,  instead  of  becoming 
more  compressed  as  it  grows  older,  continues  the  same  rate  of  increase 
in  the  transverse  diameters  The  involution  is  about  the  same  as  in 
M.  sa-alJovi,  but  there  are  no  nodes  on  the  umbiHcal  shoulders  at  any  stage, 
although  the  alternating  longer  costse  reach  to  the  umbilical  shoulders. 
Their  greatest  prominence  is  at  a  short  distan(je  ventrad  of  the 
umbilical  shoulder.  The  costations  are  like  tliose  of  the  oldest  staae  of 
whitei,  i.  e.,  regularly  long,  prominent  costfe  alternating  with  short  ones. 
The  two  outer  lines  of  tubercles  do  not  differ  from  those  of  other 
species.  The  sutures  are  intermediate  between  the  simpler  character 
of  those  of  M.  swallovi  and  the  more  complex  outlines  of  those 
of  M.  whitei.  The  first  lateral  saddles  and  lobes  have  about  the 
same  general  aspect  as  those  of  M  whitei,  but  the  auxiliaries  are 
similar  to  those  of  M.  swallovi,  except  that  the  second  lateral  saddle  shows 
small  marginals  and  a  tendency  to  division  on  its  outer  side,  which  has  not 
been  observed  elsewhere.  The  third  lateral  saddle  shows  iu  some  sutures 
of  the  left  side  a  tendency  to  become  divided,  which  is  necessarily 
exaggerated  in  the  drawing  and  which  is  entirely  absent  iu  many  sutures. 


122        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

both  younger  and  older  than  the  one  drawn.  The  dorsal  sutures  could  be 
seen  only  from  above  and  in  a  fragment  of  the  cast  of  the  last  camera, 
which  is  not  included  in  the  figures  given.  It  was  evident  that  the 
antisiphonal  lobes  resembled  those  of  M.  swallovi  and  Heinzia  in  being 
elongated  and  considerably  telescoped  into  each  other.  The  saddles  also 
were  similar,  especially  the  first  dorsals,  which  were  narrow,  long, 
phvlliform,  and  deeply  cut  into  by  the  marginals,  as  in  Heinzia  inatura. 
There  was  also  a  similar  broad  pair  of  second  lateral  dorsal  saddles;  these 
certainly  had  one  marginal  lobe  and  perhaps  two,  being  perhaps  trifid,  but 
very  flat  on  their  bases.  The  remaining  saddles  were  entire.  There  were 
apparently  five  saddles  and  four  lobes  oil  the  right  side  and  six  saddles  and 
five  lobes  on  the  left  side,  corresponding  to  the  differences  in  number  of 
the  external  auxiliaries  on  the  same  sides.  The  overlapping  of  the  sutures 
is  noticeable  in  this  specimen,  but  whether  it  can  be  considered 
characteristic  of  the  species  is  doubtful.  The  whole  diameter  is  85  mm. 
The  last  volution  on  the  face  of  the  septum  from  the  center  of  the  venter  to 
the  line  of  involution  is  50  mm.;  the  ventro-dorsal  diameter  is  35  mm. 
The  amount  of  involution  at  this  point  is  two-thirds  of  the  breadth  of  the 
side  of  the  next  inner  volution,  being  17  to  27  mm.  The  umbilicus,  in 
consequence  of  the  smoothness  of  umbilical  zones  and  the  nonextension  of 
the  costfe  internally,  has  a  smootli,  funnel-like  aspect,  entirely  distinct  from 
that  of  M.  swallovi,  although  it  is  nearly  of  the  same  size  and  differs 
therefore  from  that  of  whitei  in  being  much  larger  as  well  as  smoother. 

Locality:  Texas. 

Age:  Colorado  epoch. 

Metoicoceras  whitei  n.  sp.  Hyatt. 

PI.  Xlll,  figs.  3-.5;  PI.  XIV,  tigs  1-1(»,  15. 

BucMcerm  .noallovi  White,  1875,  Geog.  and  Geol.  Expl.  and  Surw  West  of  lOOth 

Meridian,  Vol.  IV,  p.  202,  pi.  20,  figs.  1  a-c. 
Buchiceras  swallovi  Stanton,  1894,  Bull.  U.  S.  Geol.  Survey  Ko.  106,  p.  168,  pi.  '61; 
pi.  38,  figs.  1-3. 

The  external  characteristics  of  this  species,  in  comparison  with  M. 
swallovi,  consist  in  more  compressed  volutions  without  such  prominent 
nodes  on  the  umbilical  shoulders.  They  have  nodes,  but  these  are  more  a 
part  of  the  costJE  and  less  prominent,  the  .sides  are  consequently  flatter 
than  in  swallovi.     There  is  a  decided  tendency  in  the  Texas  specimens  to 


METOICOCERATID.E.  123 

have  the  umbilicus  smaller  and  the  inner  row  of  the  two  outer  lines 
of  tubercles  elongated  loug-itudinalh'  and  parallel  with  the  outer  rows. 
The  sutures  are  more  complex  at  an  earlier  stage  and  remain  more 
complex  thi-oughout  life  as  regards  their  marginal  digitations.  The 
first  lateral  lobes  are  also  narrower  and  longer  in  proportion  in  the 
later  stages  than  in  swaUovi,  and  the  infiections  are  more  numerous 
at  the  same  age,  being  from  six  to  seven,  instead  of  five  or  six  as 
in  sivaUovi.  The  youngest  stage  seen  (PI.  XIV,  figs.  1,2)  had  a  living 
chamber  complete  near  the  umbilicus  and  not  quite  three-fourths  of  a 
volution  in  length.  Several  specimens  showed  a  completed  living 
chamber  near  the  umbilical  shoulders  and  on  the  sides,  and  in  adults  it  is 
much  shorter,  invariably  one-half  of  a  volution  in  length.  The  sides 
were  smooth  and  flat  at  the  beginning  of  the  outer  volution  in  this  specimen. 
The  costae  appeared  as  shown  in  the  figure  and  nodal  termini  were  devel- 
oped on  the  last  costation  near  the  aperture.  These  wei'e  also  present  in 
the  specimen  shown  in  fig.  4,  but,  as  may  be  seen  in  figs.  2  and  5,  these  were 
not  prominent  as  in  stvallovi.  The  same  is  true  of  all  of  the  seventeen 
specimens  examined  besides  PI.  XIII,  fig.  4  The  elongated  second  row  of 
lateral  tubercles  found  in  fig.  4  is  also  perceptible  to  some  slight  extent  in 
the  specimen  fig.  7,  but  is  absent  in  younger  stages  and  is  not  present  at 
any  stage  in  some  specimens.  This  second  row  of  tubercles  may  be  very 
slightlv  developed  in  some  specimens,  and  the  costse.  are  also  much  less 
pronounced  and  the  venters  naiTOwer  than  in  those  figured.  The  other  two 
specimens  show  a  much  stouter  form  with  brt)ader  venters  and  more  promi- 
nent costal.  These  can  only  be  separated  from  true  swallovi  by  their  costse, 
flatter  sides,  and  less  prominent  umbilical  nodes. 

An  old  suture  of  this  species  is  shown  on  PI.  XIII,  fig.  5.  This  was 
the  basal  suture  of  a  fragment  of  the  living  chamber  of  a  fossil  of  about 
the  same  size,  probably,  and  age  as  the  one  shown  on  PI.  XIII,  fig.  4. 
The  diff"erences  of  this  suture  appear  to  be  considerable  when  com- 
pared with  PI.  XIV,  fig.  8.  The  external  characters  of  this  fossil  are 
equally  decided,  but  the  absence  of  the  internal  volutions  and  the 
variability  of  the  sutures  in  this  species  does  not  justify  the 
separation  of  this  as  distinct  from  ivhitei.  The  latter  part  of 
this  living  chamber  and  the  whole  of  another  larger  fragment  has 
huge  fold-like  costse  that  cross  the  venter,  cutting  it  into  waves.  The 
costse  are  flat  on  the  venter  with  abrupt  forward  edges.     The  ventro-lateral 


124        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

tubercles  and  the  .second  lateral  row  disappear  on  these  costa?.  The 
decrease  «»f  the  involution  through  shrinkage  of  the  later  diameters  is 
greater  in  this  than  in  the  old  age  of  the  specimen  shown  on  PI.  XIII, 
fig.  4.  Breadth  of  the  side  from  line  of  involution  to  the  siphonal  saddle 
at  the  sutui'e  figured  is  65  mm.  The  length  of  the  living  chamber  on  the 
outside  or  venter  is  190  mm.  and  apparenth'  complete,  and  the  breadth  7.5 
mm.  In  the  specimen  shown  in  PI.  XIV,  fig.  7,  the  normal  rate  of  increase 
is  from  50  to  70  mm.  in  the  same  distance  measured  along  the  venter,  and 
in  the  living  chamber  of  the  fossil  shown  on  PI.  XIII,  fig.  4,  which  is  of  the 
same  length  on  the  venter  it  is  from  70  at  the  base  to  80  mm.  near  the  end- 
In  both  of  these  old  specimens  the  length  of  the  living  chamber  and 
decrease  in  the  rate  of  growth  was  therefore  about  the  same  and  about 
one-half  of  what  it  was  in  the  fossil  shown  on  PI  XIV,  fig.  7,  which  was 
also  an  old  specimen  but  was  measured  along  the  septate  and  therefore 
ywunger  poi-tion  of  the  outer  volution.  The  increase  by  growth  previous 
to  this  must  have  been  greater  still.  The  broadening  of  the  venter 
noticeable  near  the  aperture  (figs.  3  and  4),  the  spreading  of  the  costse 
across  the  venter,  and  the  loss  of  nodes  are  the  same  in.  all  three  of  these 
specimens  and  show  them  to  have  entered  upon  the  last  or  paragerontic 
substage  or  decline.  The  youngest  suture  examined  in  this  species  is 
shown  in  PI.  XIV,  fig.  3,  fi-om  the  left  side,  and  this  has  fully  entered  the 
ephebic  stage  and  is  already  more  complex  than  those  oi  swullovi  at  a  nmch 
later  age.  The  corresponding  suture  on  right  side  of  the  same  specimen  is 
similar,  but  the  third  lateral  saddle  w^as  quadrifid  instead  of  bifid  and 
the  fourth  lateral  was  more  distinctly  bifid  and  phylliform.  The  matrix  of 
this  fossil  from  Elm  Fork,  Tex.,  was  a  grav  limestone,  whei'eas  that  of  the 
specimen  shown  (fig.  9)  was  a  red  clayey  limestone,  but  from  the  same 
locality.  The  suture  was  much  older,  but  nevertheless  had  simpler  third 
and  fourth  saddles  on  both  sides  of  the  outer  volution.  The  position  of 
the  suture  of  the  specimen  shown  in  fig.  7,  given  in  fig.  8,  is  indicated  in 
fig.  7  by  a  straight  line  near  the  venter,  biit  the  sutures  throughout  this 
volution  have  the  same  outlines.  This  and  fig.  10  are  the  most  complex 
of  the  full-grown  sutures  observed  in  this  species. 

Fig.  10  was  taken  from  the  left  .side  of  PI.  XIII,  fig.  4,  and  shows 
the  outlines  of  about  the  same  age  as  in  PI.  XIII,  fig.  8.  The  shell  was 
stripped  from  a  ])art  of  the  fossil  shown  in  PI.  XIII,  fig.  4,  also,  and  the 
corresponding  suture  on  that  side  also  observed.     In  this  way  it  was  found 


MET0IC0CERAT1D.E.  125 

that  the  sutures  on  the  two  sides  differed  considerably.  They  were  alike 
in  their  first  and  second  lateral  lobes  and  saddles,  but  the  third  lateral 
saddles  were  simpler  on  the  right  side,  the  side  given  in  PI.  XIII,  fig.  4,  in 
having  the  marginals  less  distinct  and  the  fourth  lateral  was  entire  instead 
of  being  bifid.  The  outlines  internall}-  were  the  same  and  there  were 
seven  saddles  and  seven  lobes  on  each  side,  and  saddles  at  the  lines  of 
involution.  The  difterences  between  the  more  fully  developed  sutures 
on  the  left  side,  those  of  the  right,  and  the  oldest  suture  showed  similar 
degenerations,  the  saddles  becoming  much  shorter  and  broader  in  propor- 
tion and  the  marginals  less  distinct. 

The  table  on  page  126  gives  an  account  of  the  variations  observed 
in  the  sutures.  It  will  be  observed  that  the  first  lateral  lobe  is  quite 
generally  Ijirid,  but  in  the  largest  specimen  (PI.  XIV,  fig.  8)  from  Elm 
Fork,  Tex.,  it  is  sometimes  trifid.  It  is  very  obvious  that  tins  character- 
istic may  be  capable  of  two  translations,  some  of  the  first  lateral  lobes  in 
this  specimen  being  made  trifid  by  a  sHght  enlargement  and  extension  of 
the  main  terminal  marginal  lobe. 

The  second  lateral  lobe  varies  from  simple  primitive  form  of  bifidity 
to  trifid  without  regard  to  age,  but  in  most  specimens  it  is  bifid.  The  third 
lateral  saddle  is  bifid  or  trifid  without  regard  to  age,  but  tends  to  become 
quadrifid  in  older  stages.  The  fourth  varies  from  entire  t;>  bifid  or  ti-ifid, 
but  in  most  cases  is  bifid  or  trifid.  The  fifth  varies  from  entire  to  bifid  or 
trifid,  but  is  in  most  cases  entire,  sometimes  bifid  but  rarely  trifid.  The 
number  of  lobes  and  saddles  on  the  sides  varies  from  11  to  14  in  the  earlv 
ephebic  substages  and  from  13  to  16  in  the  full  grown. 

No.  6  is  taken  from  a  fossil  with  a  notably  stouter  volution,  more 
prominent  coarser  costa?,  and  larger  tubercles  than  any  of  its  companions 
of  the  same  size  from  the  same  locality,  Elm  Fork,  Tex  The  whole 
diameter  of  this  fossil  when  complete  was  probably  not  less  than  63  mm. 
and  the  living  chamber  of  the  usual  length,  a  little  over  half  of  a  volution. 
Unluckily,  like  all  others  of  this  species,  the  aperture  has  been  badly 
broken  and  the  rostrum  could  nut  be  observed.  I  at  first  thouffht  this 
exceptionally  stout  and  more  coarsely  ornamented  specimen  must  be  a 
different  species,  but  the  sutures,  when  laid  bare,  were  identical  with 
others  here  described  as  M.  tvhitei,  especially  close  to  that  given  on  PI 
XIV,  fig.  10. 


126 


PSEUDOCERATITES  OF  THE  CRETACEOUS. 


Variations  observed  in  sutures  of  2Ietoicoceras  whitei. 

[The  number  of  saddles  and  lobes  represents  one  side  only.    All  except  Nos.  11,  12,  and  15  are  from  Elm  Fork,  Hortons 
mill,  Dallas  County,  Tex.;  No.  15  is  from  Utah;  no  locality  is  given  for  Nos.  11  and  12,] 


Speci- 
men. 


10. 


11. 


12. 


13. 


14. 

15. 


Side 
observed. 


rLeft... 

iRight  . 

fLeft... 
2        .  X 

iRight  . 

'  fLeft... 

^ iRight  . 

fLeft... 

iRight  . 

!  fLeft... 

^ |lRight. 

fLeft... 

IRight  . 

fLeft... 

' jlRight  . 

I  fLeft... 

^ |lRight  . 

Left . . . 


Length  of 
suture 
line  or 
breadth 
of  side. 


I  Right 
fLeft.. 
IRight 
fLeft.. 
iRight 
Left.., 
\Right 
fLeft . . . 
iRight  , 


fLeft... 
IRight  , 
J  Left... 
I  Right 


10 


13 


17 


17 


23 


23 


28 


31 


34 


35 


39 


45 


55 


65 
70 


First  lat- 
eral lobe. 


f  Bifid. 

I. .do  . 

fBifid? 

I     (?) 

^Bifid . 

l  (?) 
(?) 
(?) 
(?) 
(?) 

fBifid. 

I     (?) 

I     ^'^ 
I     (?) 

I     ^'^ 
iBifid. 

I     *'^ 
I     (?) 

f  Bifid  . 

I.. do  . 

f..do  . 

I. .do  . 

f..do  ., 

I     (?) 

/^Bifld., 

.do  ., 


..do  . 

(?) 
fBifid  . 
I.. do  . 


Second 
lateral 
lobe. 


Third  lat^ 

eral  sad 

die. 


Trifid 
...do  . 

(?) 
(?) 
(?) 
(?) 
(?) 
(?) 
(?) 

Bifid. 
...do  . 
(?) 
(?) 
(?) 
(?) 

Trifid 

(?) 
(?) 

Bifid. 

...do  . 

...do  . 

...do  . 
(?) 
(?) 

Bifid  . 

...do  . 


..do  .. 

(?) 

Bifid. 
..do.. 


Trifid 
...do.a 
...do  . 
..do  . 
...do  . 

(?) 

(?) 
Trifid." 

(?) 
Trifid  . 
Bifid!/. 

(?) 
Bifid.. 

(?) 

(?) 
Bifid !-. 
Trifid" 
,..do.n. 
Bifid . . 
...do  .. 
Trifid  . 
...do.n. 
...do  .. 
..do  .. 
..do.''. 
.  .do.  f. 


Bifid  <-■. 

(?) 
4-fid  .. 
...do.9. 


Fourth  Fifth  lat- 
lateral  eral  sad- 
saddle.    !      die. 


Bifid.. 
...do  .. 
Entire? 
...do.?. 
Trifid  . 

(?) 

(?) 
Trifid  . 

(?) 
Bifid  . . 
...do  .. 

(?) 
Trifid? 

(?) 

(?) 

Trifid  . 

(?) 
Entire. 
...do  .. 
...do  .. 
...do  .. 
...do  .. 
...do  .. 

(?) 
Bifid  . . 
Varia- 

ble..r' 


Trifid  . 

(?) 
Trifid  . 


Entire. 

(?) 

(?) 

(?) 

Entire. 

(?) 

(?) 

Trifid  . 

(?) 

Entire 

...do  .. 

(?) 
Entire. 

(?) 

(?) 

Bifid.. 

(?) 
Entire. 
...do  .. 
...do  .. 
...do  .. 
...do  .. 
...do  .. 

(?) 

Entire. 

...do  .. 


Bifid., 

(?) 
(?) 


Bifid  . .    Entire. 


Number 
of  saddles 
and  lobes 

on  sides. 


j  Number 
>of  saddles 
j  and  lobes 
on  dor- 
sum. 


'  'I 
11  \> 


(?)  j 

(?)  ,' 

(?)  ' 

(?)  , 

11  / 

(?)  \ 

(?)  i' 

(?)  ' 

"  } 

(?)  ' 

(?)  i 


13 :/ 


(?) 


13'? 

16 

16 

13 

13? 

13? 

13? 

15, 

15   / 


15 


(?) 


13'; 
13 


(?) 
(?) 
(?) 
(?) 
(?) 
(?) 
(?) 

10 

(?) 
(?) 
(?) 
(?) 
(?) 


(?) 
(?) 


Figured. 


PI.       XIV, 
figs.  1-3. 


PI.      XIV, 
figs.  4-6. 


PI.         XV, 

fig.  15. 


PI.       XIV, 
fig.  9. 


PI.  XIII, 
figs.  3,4, 
and  PI. 
XIV,  fig. 
10. 

PI.  XIII, 
fig.  5. 

PI.  XIV, 
figs.  7,8. 


a  Beginning  to  become  quadrifid,  i.  e.,  having  four  minute  marginal  saddles  by  division  of  one  of  the  bifld  marginals. 

^\Vith  a  few  minute  digitations  beginning  to  appeiir. 

c  With  three  other  very  minute  lobes,  five  marginal  lobes  in  all. 

dDistinctly  trifid. 

<  Obscurely  trifid. 

/Some  entire,  others  obsouroly  trifid. 

uWith  a  number  of  small  marginals  just  beginning. 


METOICOCERATID.E.  127 

lu  all  of  these  specimens  the  hrst  lateral  saddles  were  of  very  nearly 
the  same  general  character,  decidedly  deeply  bifid,  even  in  the  youngest 
stages  recorded,  and  with  both  arms  subdivided  by  one  or  more  marginal 
lobes;  the  second  lateral  saddles  were  also  complex  at  all  stages  observed, 
and  one  small  specimen  not  recorded  in  the  table,  with  suture  lines  on  the 
last  volution  running  from  12  to  18  mm.,  showed  the  same  facts.  This  has 
bifid  first  and  trifid  second  lateral  lobes,  with  quadrifid  third  lateral  saddles 
on  both  sides.  A  bifid  fourth  is  visible  on  the  right  side  when  the  volution 
is  less  than  12  mm.  This  same  saddle  with  a  bifid  base  is  the  only  one 
visible  in  another  fossil  with  a  suture  line  of  about  8  mm.  It  is  evident 
that  the  law  of  variation  in  the  sutures  is  that  lobes  and  saddles  increase 
in  variability  of  outlines  and  in  number  progressively  from  the  venter 
toward  the  dorsal  lines  of  involution,  the  so-called  auxiliaries  or  derivatives 
of  the  primitive  second  lateral  saddles  of  the  young  being  far  more  variable 
than  the  first  lateral  saddle. 

Locality:  Kanab  Valley,  Utah;    Elm  Fork,  Dallas  County,  Tex. 

Age:  Colorado  epoch. 

Metoicoceras  acceleratum  n.  sp.  Hyatt 

PI.  XIV,  tigs.  ll-U. 

I  at  first  thought  this  to  be  the  young  of  the  species  described  by 
Whiteaves  as  Placenticeras  liardense,  but  the  figures  given  b}^  him  merely 
indicate  that  the  venter  had  continuous  costte  across  it.  The  condition  of 
his  fossils  was,  however,  such  that  he  did  not  see  the  venter,  and  this 
can  only  be  inferred  from  the  lateral  aspect  as  given  in  his  drawings. 
Apparently  there  were  no  tubercles  on  the  sides  in  the  full-grown  specimen, 
and  the  umbilicus  was  about  the  size  of  that  of  M.  ivhitei  and  not  so  small 
as  in  this  species.  There  were  no  nodes  nor  prominent  costse  near  the 
umbilical  shoulder  in  this  fossil,  and  the  two  outer  rows  of  tubercles  were 
much  less  prominent  than  in  the  preceding  species.  The  venter  in  the 
first  half  of  the  outer  volution  resembled  that  of  M.  whitei  at  an  earlier  age 
on  the  first  quarter  of  the  outer  volution  of  the  specimen  shown  in  PI.  XIV, 
fig.  1 ,  but  with  less  decided  tubercles,  and  on  the  latter  half  of  this  volution 
it  is  changed  as  the  venter  is  in  the  old  age  of  M.  whitei.  That  is  to  say, 
the  costse  that  cross  it  are  prominent  and  flat,  but  not  channeled  nor 
concave.     The  costse  on  the  sides  are  not  so  prominent  and  coarse  as  in 


128        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

whitei.  There  are  more  of  tlieni,  and  imly  the  hist  begin  to  reach  entirely 
across  the  sides.  There  is  a  signioidal  channel  on  either  side  that  does 
not  reach  across  the  venter.  This  is  a  characteristic  occurring-  also  in 
M.  liardense,  but  not  in  other  species.  This  occurs  close  to  what  must  have 
been  the  edge  of  the  aperture,  since  the  hving  chamber  is  considerably 
over  tlu-ee-fourths  of  a  volution  in  length  and  was  probably  a  little  longer 
when  complete.  The  black  line  shows  the  position  of  the  basal  septum  of 
the  li-viug  chamber  shown  on  the  opposite  side  of  the  fossil  figured. 

Locality:  Elm  Fork,  Horton's  mill,  Dallas  County,  Tex. 

Age:  Colorado  epoch. 

HEINZIID^. 

The  members  of  this  famih'  are  easily  distinguishable  from  the  typical 
Pulchelliidse  by  the  possession  at  some  stage  of  elongated,  usually 
double,  but  more  or  less  connected  tubercular  terminations  on  the  ventral 
ends  of  the  lateral  costse.  All  of  the  foi-ms  so  far  known  have  coarser  and 
more  complete  lateral  costse  than  are  usual  in  Pulchelliidpe,  and  there  is, 
especially  in  primitive  forms,  a  tendenc}^  to  the  development  of  stouter 
volutions,  with  less  involution  and  consequently  wider  umbilici.  The 
average  size  is  larger,  and  the  development  is  very  distinct  in  all  forms,  so 
far  as  known.  The  young  are  stouter,  less  involute,  and  have  costse  con- 
tinuous across  the  venter.  The  tubercles  appear  upon  these  costse  in  two 
lines  of  single  tubercles,  and  then  subsequently  two  rows  are  developed 
ujjon  the  outer  sides  of  these  that  remain  more  or  less  closely  connected. 
The  lateral  costae  are  similar  to  those  of  Pulchelliidfe,  but  sometimes  a 
median  or  an  inner  row  of  tubercles  or  both  appear  in  the  later  stages. 
The  ventral  channels  are  apt  to  be  real  channels  furrowing  both  the  costae 
and  the  intercostal  spaces  on  the  venter,  and  in  the  young  and  in  primitive 
forms  are  apt  to  be  narrow  and  smooth.  The  sutures  are  similar  to  those 
of  Pulchelliidaj,  but  as  a  rule  have  fewer  and  larger  saddles  and  lobes,  and 
the  outlines  more  complex  at  the  same  comparative  age,  judging  from  the 
size  of  the  casts. 

The  development  is  so  distinct  from  that  of  Pulchelliidse  in  some  species 
of  Heinzia  that  if  it  were  not  for  the  fortunate  accident  that  placed  one 
specimen  of  Heinzia  matiira  in  my  way,  I  could  not  have  offered  any 
rational  suggestion  as  to  the  true  relations  of  this  family.  The  development 
of  Heinzia  matura,  however,  shows,  as  stated  below,  a  form  that  in  the 


HEINZIID.E.  1 29 

young-  is  involute,  smooth,  and  compressed  with  a  rounded  venter  as  in  the 
young  of  Pulchelhida?.  Then  it  has  a  faint  hne  of  ventral  tubercles  and 
flat  venter  followed  bv  a  true  Pulchellian  stag-e  with  channeled  venter 
bordered  by  single  tubercles.  In  other  words,  at  this  age  the  species  is 
like  PuJcheUia  except  that  the  tubercles  are  not  elongated  crests.  The 
ephebic  stage  shows  the  usual  terminal  double  row  of  tubercles  of  the 
Heinziida?.  The  conclusion  from  this  evidence  is  that  the  Pulchelliidae 
probably  arose  from  Heinzia  or  some  ver}-  similar  form  through  the  increase 
of  compression  and  involution  and  from  the  prolongation  of  the  smooth 
larval  stages,  the  suppression  of  the  preliminary  lines  of  ventral  tubercles 
in  the  young  and  the  tendency  in  later  stages  to  suppress  the  second  lateral 
lines  of  tubercles.  This  inference  acquires  some  support  also  from  the  fact 
of  the  earlier  appearance  of  Heinziida?  in  the  Neocomian.  We  can  in  this 
way  account  for  the  communal  resemblances  of  these  two  families  in  their 
adult  forms,  costse  and  sutxires,  but  it  must  be  borne  in  mind  that  the  evi- 
dence upon  which  this  inference  is  based  is  not  by  any  means  complete. 
The  evidence  with  regard  to  the  connection  and  genesis  of  forms  is 
less  complete  than  in  the  Pulchelliida?,  but  the  following  diagram  gives  the 
apparent  relations  of  the  genera  so  far  as  the  ontogeny  at  jjresent  known 
indicates  these: 

Metoicoceras 
Gerhardtia     Carstenia 


-Heinzia 


Cheloniceras 

HEINZIA  Sayn. 

Sayn"  defines  this  genus  in  the  following  terms:  "Les  espfeces  qui  se 
rattachent  aux  PulcheUia  subcaicedi  et  provincialis  sont  nettement  caracter- 
is^es  par  une  ornementation  vigoureuse,  visible  dfes  les  tours  embryonnaires, 
un  accroissement  en  ge'neral  moins  rapide,  des  sutures  le  plus  souvent  tres 
<jloignees  les  unes  des  autres  et  remarquables  par  le  grand  d(^veloppement 
en  largeur  des  selles  et  I'amoiudrissement  des  lobes  trfes  (itroits  et  pen 
d^couptis."     The  group  described  by  Sayn  under  this  name  is  obviously  a 

oAmiiJ.  <lu  Barremien  du  Djebel-Ouach  pres  Constantine:  Ann.  Soc.  d' Agriculture  de  Lyon,  6th 
aeries,  Vol.  Ill,  1890,  p.  151. 

MON  XLIV — 03 y 


130        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

composite  of  several  geuera  distinct  in  their  development  and  in  their 
sutures  from  any  fonn  of  true  Pulchelliida^  and  also  differing  decidedly 
from  each  other.  The  species  here  mentioned  as  H.  sayni  is  assumed  to  be 
the  type  because  it  is  one  of  the  first  two  species  mentioned  by  this  author 
and  is  the  first  one  of  these  figured.  His  PulcheUia  subcaicedi  appears  to 
me  to  belong  with  PulcheUia  caicecU  (Karsten)  in  the  genus  Carstenia. 

Heinzia  sayni  Hyatt 

J'lilcJiellia  provincialis  Saj'ii,  1890,  Aun.  Soc.  d'Agriculture  de  Lyon,  6th   series, 
Vol.  Ill,  pp.  165,  166;  pi.  1,  fig.  16;  pi.  2,  fig.  7. 

This  is  neither  the  species  figured  by  d'Orbigny  nor  that  given  by 
Nicklfes,  but  a  dwarfed,  compressed  form  with  fine  tubercles  and  fine  costae 
developed  at  a  comparatively  early  stage.  It  is  similar  to  true  H.  provin- 
cialis  in  being  less  involute  than  corioll. 

Locality:  Djebel-Ouach,  North  Africa. 
Age :  Barremieu. 

Heinzia  corioli  Nicklfes. 

I'ulchellia  {Heinzia)  corioli  Nickles,  ISyO,  Mem.  Soc.  geol.  France,  Paleontologie, 
No.  4,  p.  53,  pis.  6,  7. 

This  species  and  another,  supposed  to  be  allied  to  sayni,  are  both 
larger,  have  coarser  ornaments  and  more  complex  sutures  than  the  African 
forms,  and  broad  channels  like  Gerhardtia. 

Locality:   Spain. 

Aye:  Barremian. 

Heinzia  heinzi  Coquand" 

PulcJtellia  heinzi  Sayn,  1890,  Ann.  Soc.  d'Agriculture  de  Lyon,  6th  series.  Vol.  IH, 
pi.  2,  fig.  5. 

This  species  has  similar  ornamentation,  but  much  coarser  than  in 
H.  sayni.  The  sutures  are  given,  and  these  are  not  similar  to  those  of 
Pulchellidee. 

Locality:   North  Afric?.. 

Age:  BaiTemian. 

"Coronites  ii?  represented  in  North  Africa  by  a  8mall  group  of  dwarfed  forms  having  the  develop- 
ment and  general  aspect  of  the  more  discoidal  forms  of  Hopliteii.  The  ty])e  is  Cur.  ( Heinzia )  curniiatoides 
(Sayn).  This  form  has  a  ventral  channel,  beginning  at  a  comparatively  early  stage  while  the  young 
are  still  highly  coronate  and  the  costic  dichotomouson  the  venter.  These  spring  from  single  nodes  en 
the  latero-ventral  angles,  which  are  coincident  with   the  umbilical   shoulder.     These  subsequently 


HEINZIID^.  131 

Heinzia  hispanica  n.  sp.  Hyatt. 

PulchelUa  {Heinzi(()  cf.  provinciaUs  Nickles,  Mem.  Soc.  geol.  France,  Paleontologie, 
No.  4,  pis.  6,  7. 

Nickl^s's  figures  o-ive  a  sjDecies  with  smaller  mnbiliciis  and  a  shallower, 
wider  channel  furrowing  the  costfe  only,  as  in  PulcheUia.  The  costae  have 
more  prominent  nodes  and  are  more  prominent  on  the  venter,  which  is 
crossed  by  them  and  cut  up  into  waves  as  in  PulchelUa. 

There  is  one  specimen  in  the  Museum  of  Comparative  Zoology,  prob- 
ably from  Escragnolles,  that  I  have  labeled  Heinzia  atf.  hispanica.  It 
difters  from  this  species  only  in  having  more  involute  whorls  and  perhaps 
somewhat  coarser  costae  and  possibly  the  sutures  a  little  more  complex. 

Heinzia  pulchellipormis  n.  sp.  Hyatt. 

Thi.s  species,  from  the  collection  in  the  Museum  of  Comparative  Zoology, 
has  exactly  the  form  and  aspect  of  some  of  the  typical  species  of  PulchelUa, 
except  that  the  costse  are  more  prominent  and  cross  the  inner  parts  of  the 
sides,  and  the  outer  row  of  tubercles  has  the  broad,  double  character  of 
those  of  the  Heinzia  group.  This  has  no  inner  line  of  tubercles  and  has 
been  considered  similar  to  didayanu.s,  which  is  a  species  v{  Nicklesia. 

LovalHy:  Escragnolles,  France. 

Age :   Barremian. 

Heinzia  provincialis  (d'Orbigny). 

PI.  XV,  figs.  19, 20:  PI.  XVI,  figs.  1-3. 

ArawMnites  provincialis  d'Orbigny,  1850,  Prodrome  de  Paleontologie,  Vol.  II,  p.  99. 
PiAcaellia  provinciaUs  Uhlig,  18S3,  Denksch.  K.  Akad.  Wiss.,  Wien,  Vol.  XLVI, 
pi.  20,  fig.  2. 

Assuming  Uhlig's  figure  to  be  taken  from  a  species  identical  with 
d'Orbigny's,  the  specimen  here  figured   is  a  true   representation   of  this 

extend  internally  into  lateral  single  costje  and  the  nodes  disappear.  The  cost*  become  single  on  the 
sides  or  may  remain  dichotomous.  The  result  is  a  form  in  some  species  that  is  almost  an  exact 
parallel  with  some  forms  of  the  Hop litidse.  The  sutures  are  simple  and  have  an  immature  aspect. 
The  ventral  is  rather  narrow  and  is  divided  by  a  small  truncated  siphonal  saddle.  The  first  lateral 
saddles  are  very  broad,  bifid  on  one  side  in  II.  hopW^ormh  and  trifid  and  still  broader  on  the  other. 
The  first  lateral  lobes  are  narrow  and  trifid  or  bifid.  The  second  lateral  saddles  belong  to  the  auxiliary 
series,  and  are  much  smaller  than  the  first  and  only  slightly  dentated,  while  the  third  and  fourth 
saddles  are  entire.  The  second  lateral  lobe  is  very  short  and  entire,  and  two  other  similar  smaller 
lobes  complete  the  lateral  line. 

This  description  is  taken  from  Sayn's  figures. 


132        PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

species.  It  has  the  narrow,  deep,  smooth  ventral  channel,  which  is  also 
shown  in  Uhlig's  figure,  with  the  same  peculiar  abrupt  ventral  terminations 
to  the  costw  with  forward  bend  on  the  edge  of  the  channel.  The  venter  is 
not  cut  up  into  waves  by  the  crossing  of  the  costpe  as  in  H.  ptiJchelViformis. 
The  channel,  in  fact,  is  deeper  than  the  depressions  between  the  costaj,  and 
the  ridges  that  guard  it  on  either  ridge  give  a  pointed  aspect  t<>  the  forward 
terminations  of  the  costse.     This  is  also  observable  in  Uhlig's  figure. 

On  splitting  this  specimen  I  succeeded  in  exposing  three  substages 
of  neanic  age.  The  first  substage  showed  faint  costa?  that  crossed  the 
rounded  venter,  the  form  being  at  this  time  rounded,  with  gibbous  sides  and 
oj)eu  umbilicus.  Then  faint  tubercles  appeared,  the  venter  still  remaining 
rounded  between  them.  These  tubercles  in  the  next  su^bstage  became  more 
prominent,  and  the  venter  between  them  became  flattened.  The  costae 
became  more  prominent  at  the  same  time  on  the  outer  half  of  the  side  and 
made  a  slight  forward  liend  on  to  the  venter.  Soon  after  this  a  very  faint, 
narrow,  linear  depression  indicated  the  beginning  of  the  ventral  chaiuiel. 
I  was  not  able  to  discover  at  what  age  the  second  range  of  tubercles  began 
to  come  in  nor  their  exact  position.  The  volution  is  gibbous  on  the  sides 
throughout  these  early  stages  and  is  a' rather  stout  young  form  with  an  open 
umbilicus. 

Locality:  Escragnolles,  France. 

Aye:  Barremian. 

Heinzia  matura  n.  sp.  Hyatt. 
PI.  XV,  figs.  12-18. 

This  species  is  allied  to  that  described  alcove  by  Sayn.  It  is  similar 
in  its  compressed  form,  in  the  amount  of  involution  and  in  the  broad 
ventral  channel,  and  in  having  a  row  of  tubercles  on  the  umbilical  shoul- 
ders. The  costaj  are,  however,  much  broader  and  have  the  double  external 
termination  of  the  group  of  Heinzia.  This  termination  is,  however,  not 
distinguishable  on  the  earliest  part  of  the  outer  volution,  but  is  well  devel- 
oped on  the  third  (piai-fer  of  this  volution.  This  termination  is  seen  in  this 
specimen  to  be  a  modification  of  the  ends  of  the  costa?,  and  it  is  not  due  to 
tlie  a})i)roximation  and  coalescence  of  an  inner  row  of  tubercles  with  the 
outer  row.     The  shell  is  preserved  on  one  side  of  this  specimen  and  shows 


HEINZIID^E.  133 

the  same  marking-s  as  on  the  cast.  The  }';oaiig  is  much  flatter  and  increases 
faster  in  the  abclomino-dorsal  diameters  than  in  other  s^jecies  of  Heinzia  and 
remains  smooth  until  a  later  ag-e.  The  tubercles  appear  also  later  on  the 
venter,  and  there  is  a  flat  ventral  zone  for  a  more  prolonged  stage  than  in 
H.  jiroviticiaUs,  and  the  ventral  channel  appears  later.  The  umbilical 
tubercles  appear  on  the  last  volution  figured  and  are  at  first  single.  Then 
they  probably  become  [double]  by  the  development  of  two  other  roA^s  of 
tubercles  near  the  ventral  lines,  but  this  was  not  actually  seen  on  the 
specimen. 

Locality:  Escraguolles,  France. 

Ar/f:    Barremian. 

Heinzia  ouachensis  (Coquand). 

Pulchellia  oioichtnsix   Sayn,    1890.  Ann.   Soc.   d' Agriculture    de  Lyon,    ((th  series, 
Vol.  III.  p.  1.57,  pi.  1.  tig.  1.5  (not  fig.  14). 

This  species,  described  as  a  Pulchellia  by  Sayn,  is  an  involute  com- 
pressed form  probably  in  the  same  genetic  group  with  H.  matura.  This  is 
shown  by  the  ventral  channel  and  costse  and  tubercles  on  the  umbihcal 
shoulders.  It  has  not  the  broad  double  terminations  of  the  costaj  observed 
in  H.  matura.  Fig.  15  is  probably  a  true  PulcheUia,  and  is  cited  under  that 
generic  name  as  P.  kiliani. 

Locality:  Djebel-Ouach,  North  Africa. 

Age:  Barremiau. 

CARSTENIA  n.  gen.  Hyatt. 

This  remarkable  group  has,  as  shown  by  Karsten's  figure  of  Carstenia 
lindigi  in  the  latest  neanic  or  early  ephebic  stage,  coarse  costpe  with  double 
terminations  liecoming  dichotomous  at  the  middle  lateral  line  and  havino-  a 
line  of  nodes  at  their  junctions.  These  are  continued  later  on  the  single 
costse  when  these  appear.  The  arising  of  the  double  line  of  outer  tubercles 
close  together  on  the  ventral  line  is  also  shown  in  this  figure.  The  form  is 
stout  in  the  type  mentioned  above  and  similar  to  that  of  Heinzia  provincialis, 
but  in  the  Carstenia  (Amm.)  caicedi  Karsten  it  is  more  involute  and  com- 
pressed. The  ventral  furrow  in  Carstenia  lindigi  in  the  young  is  narrow 
and  similar  to  that  of  Heinzia,  but  later  it  broadens  and  becomes  similar  to 


134        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

that  of  Gerliardtia.      This   occurs  in    an   earlier  age   in   Carstenia  caicedi. 
Descriptions  are  wholly  taken  from  Karsten's  figures." 

Carstenia  subcaicrui  (Karsten). 

C.  subcaicedi  (Karsten)  is  described  ))y  that  author  as  having  heavy 
coarse  costse  bifurcating  like  those  of  caicedi  and,  if  his  small  figure 
represents  the  young  or  a  primitive  dwarfed  form  of  this  group,  it  shows 
how  very  distinct  its  development  must  be  as  compared  with  that  of  other 


genera. 


Carstenia  ?  tuberculata  n.  sp.  Hyatt. 


C.  f  tuberculata  (Pul.  provincialis  Gerhardt) ''  is  described  by  that  author 
as  identical  with  lindigi  Karsten.  It  is,  however,  less  involute,  and, 
although  having  similar  quadragonal  volutions,  has  costa?  like  those  of 
Gerhardtla  and  there  is  no  median  lateral  line  of  tubei'cles.  The  sutures 
are  more  like  those  of  Metoicoceras  than  of  Heinzia  iwovincialis.  It  is 
jjossible  that  the  development  of  this  species  may  show  it  to  be  more  nearly 
related  to  Metoicoceras  than  to  Carstenia.  It  has,  however,  the  peculiar 
channeled  bases  of  the  second  row  of  tubercles  on  either  side  that  have 
been  found  so  far  only  in  this  last-named  genus.  All  of  these  have  been 
supposed  to  be  of  Barremian  age.  Its  characteristics  seem  also  to  ally  it 
decidedly  with  such  forms  as  Heinzia  provinciaUs,  and  to  indicate  a  common 
origin  for  all  of  these  genera  in  some  primitive  form  with  similar  but  more 
tuberculose  volutions.  It  is  obviously  a  more  primitive  form  than  Heinzia, 
which  has  more  compressed  and  often  more  involute  shells  and  retains  in 
its  latest  stage  the  form  and  aspect  of  the  young  of  H.  iwovincialis  and  of 
the  earlier  neanic  stage  of  Metoicoceras  sivallovi.  The  resemblances  to 
Gerliardtia  are  also  close,  as  may  be  seen  on  Gerhardt's  plates,  and  its 
form  is  similar  to  the  young  of  Carstenia  caicedi  as  figured  hy  Karsten. 

These  affinities  and  its  obviously  primitive  larval  characteristics  show 
it  to  be  the  nearest  approach  yet  found  of  the  probable  genetic  ancestor  of 
the  Heinziidie. 


«Geol.  de  I'ancienne  Colomb.  Venez.  Nouv.  Gren.  et  Ecuador.     Berlin,  1886. 
SKreidef.  in  Columbien:  Neues  Jahrbucli  fiir  Min.,  Oeol.,  und  Pal.,  Beil.-Bd.  XI,  1897-98,  p.  1.52, 
pi.  2,  fig.  8. 


HEINZ1ID.E.  135 

Carstenia  galeata  (d'Orbigny). 

Ammonites  galeatus  d'Orbigny,  1842,  Voya<?e  dans  rAmerique  meridionale.  Vol.  III. 

pi.  17,  figs.  3-.5  (not  figs.  6,  7). 
PidehelUa  caicedi  Gerhardt,  1897,  Neues  Jahrb.  fiir  Min.,  Geol.,  und  Pal.,  Beil.-Bd. 

XI,  p.  151,  pi.  3,  fig.  7. 

This  species  has  a  form,  costse,  ventral  channel,  and  outer  tubercles 
similar  to  those  of  C.  caicedi  Karsten,  but  having  the  single  costaj  appearing 
later,  the  double  outer  line  of  tubercles  disappearing  at  the  same  time,  and 
no  median  lateral  line  of  tubercles  apparent  in  d'Orbigny's  figures.  The 
double  outer  tubercles  are  observable  in  figures  given  by  d'Orbigny  at  the 
beo-inning  of  the  outer  volution  and  are  quite  plain  upon  an  excellent  cast 
of  this  fossil  from  Chile  in  De  Koniuek's  collection  in  the  Museum  of 
Comparative  Zoology.  Figs.  6  and  7  of  d'Orbig-ny  are  true  PtdcheUia,  not 
the  young  of  this  species.  Pul  caicedi  Gerhardt  has  exactly  the  form  and 
aspect  of  the  next  younger  parts  of  the  volution  figured  by  d'Orbigny  and 
observable  on  the  last  mentioned. 

GERHARDTIA  n.  gen.  Hyatt. 

The  near  alliance  of  this  genus  with  Heinsia  becomes  apparent  upon 
compai-ison  of  the  type  Gerhardtia  r/aleatoides  (Karsten)  with  Heinda 
provincialis  (d'Orb.)  and  Heinzia  ?  fuhercidata.  The  umbilical  characters 
are  similar  so  far  as  the  amount  of  involution  and  tlie  general  aspect  is 
concerned,  but  the  umbilical  shoulders  are  more  prominent,  the  umbilical 
zone  is  sometimes  concave,  broader,  and  the  umbihcus  deeper.  The  shell 
in  the  neanic  and  adult  stage  is  more  compressed  and  more  involute  than 
it  is  in  Heinzia  at  the  same  age  and  also  more  involute  than  its  own 
ephebic  stage.  The  extreme  decrease  of  involution  in  old  specimens  may 
also  be  noticed  in  these  forms.  The  costte  in  the  neanic  stage  are  much 
finer  and  more  closely  crowded  than  in  anj-  genus  of  this  group.  The 
costfE  are  similar,  but  the  outer  row  of  douljle  nodes  are  absent  or  only 
very  faintly  expressed.  The  sutures  are  more  complex  in  outline,  but  of 
the  same  general  type. 

The  form  is  more  compressed,  the  venter  more  contracted,  and  practi- 
cally bounded  by  the  elongated  single  nodal  termini  of  the  costas.  The 
furrows  between  the  costse  cross  the  venter,  cutting  it  u.p  into  flexures,  and 
the  ventral  channel  is  very  broad  and  affects  the  flexures  only,  not  descend- 
ing to  the  level  of  the  ventral  furrows. 


1B(5        PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

Besides  the  type  mentioned  above,  this  gronp  contains  Ger.  fialeatus 
(Karsteu)  (von  Buch's  figure  of  this  species  is  too  poor  for  comparison),  and 
Ger.  veleziensw  u.  sp.  Hyatt  (P»/.  didayi  Gei'h.,  op.  cit.,  pi.  3,  fig.  4).  Amm. 
didaijanus  d'Orb.  belongs  to  genus  NicMesia.  Anim.  didayaims  Karsteu  is 
probably  a  younger  stage  of  tlie  species  figured  by  Gerhardt,  and  it  came 
from  the  same  locality,  Velez. 

Similar  species  have  been  cited  from  other  countries  by  Gerhardt,  l)ut 
tliese  are  unknown  to  me. 

All  species  are  of  Barremian  age  and  found  in  Colombia  or  Chile. 

The  sutures  have  been  well  figured  by  Gerhardt  and  are  quite  difi'erent 
from  those  of  C.  tuberculata  and  H.  provincialis. 

PULCHELLIID^. 

This  family  has  highly  involute  comj)ressed  shells.  The  costa%  when 
these  are  present,  are  acquired  at  a  comparatively  late  age,  and  the  tuber- 
cles, when  i)resent,  are  single  elongated  crests  on  the  ventro-lateral  angles 
of  the  costpe.  The  costa-  usually  cross  the  venter  even  when  there  is  a 
channel  on  their  outer  surfaces.  The  sunken  intercostal  furrows  that  cross 
the  venter  also  are  not  as  a  rule  aftected  by  the  channeling  of  the  costa?. 

The  sutures  are  of  the  same  type  as  in  Heinzla,  but  with  somewhat 
more  complex  outlines.  I  have  had  no  opportunity  to  examine  the  dorsal 
sutures. 

The  primitive  form  is  PsilojiulcheUia,"  which  retains  the  smooth keelless 
condition  of  its  own.  young  throughout  life.  This  stage  is  transient  in  the 
development  of  other  genera.  In  Xicklesia  it  is  followed  by  a  stage  with  a 
flat  venter,  and  this  is  then  followed  by  the  development  of  lateral  costje 
that  cross  the  venter  without  tubercles  or  channels,  or  the  latter  may  be 
developed  directly  from  the  previous  stage. 

Sidipidchellia  has  similar  stages  followed  by  a  channeled  venter  due  to 
the  development  of  two  slight  ridges. 

Ptdchellia  develops  lateral  costae  that  cross  the  venter,  but  these  are 
concave  on  the  venter  and  have  lateral  tubercular  crests  in  place  of  the 
ridges  of  Suhpulchdlia.  The  intercostal  furrows  also  cross  the  venter,  but 
are  usuall}'  convex  on  the  venter  between  the  costae.  The  tubercles  have 
been  universally  but  erroneously  spoken  of  as  keels.     They  are  really  not 

"  Tlie  author  failed  to  describe  or  cite  any  species  belonging  to  Psilopulchellia. — T.  W.  S. 


PULCHELLIID.E.  137 

coutiuuous  at  any  stage  and  can  not  even  be  accurately  described  as  ridges. 
The  term  carina  or  keel  should  be  confined  entirely  to  the  continuous 
azygous  ventral  elevation.  The  term  bicarinate  is  confusing  and  might  be 
especially  troublesome  if  occasion  should  arise  to  describe  a  form  having 
a  really  double  or  split  keel.  A  further  modification  of  the  development 
takes  place  when  a  keel  arises  upon  the  smooth  rounded  venter  of  the 
earlier  stages  as  in  PsUotissotia.  This  form  is  apparently  transitional  to 
true  Tissotida?,  but  these  affinities  disappear  upon  comparing  the  ontogeny 
with  that  of  Tissotiida?,  and  especially  when  the  relations  of  these  to  the 
flat  ventered  and  keeled  and  channeled  forms  of  Pseudotissotia  are  recog- 
nized. The  sutures  of  PsUotissotia  are  also  decidedly  Pulchellian  and  there 
are  also  transitional  forms  connecting  it  with  PsUopidcheUia.  Lopholobites, 
so  far  as  known,  appears  to  be  adequately  accounted  for  as  a  retrogressive 
modification  of  PsUotissotia  or  some  of  the  smooth  forms  with  which  it 
agrees  in  external  characters.  This  suggestion  requires,  of  course,  to  be 
tested  by  the  comparative  study  of  its  development  and  that  of  the  similar 
forms  of  this  family."  The  natural  arrangement  of  these  genera  upon  the 
basis  of  their  ontogeny  seems  therefore  to  be  as  follows : 

Piilchellia 

I 
Nicklesia    Subpulohellia    Psilotissotia 

I  I  I 

'- Psilopulchellia '■ Lopholobites 

J     . 
Heinzia 

It  seems  obvious  from  the  development  of  the  young  of  most  genera 
and  the  apparently  full-grown  SubpidcheUia,  and  from  the  evidence  of  the 
sutures,  that  this  group  is  closely  related  to  Engonoceratidae.  If  this  be  so, 
the  latter  can  be  explained  as  a  retrogressive  form  evolved  from  Siibjndchel- 
lia  as  its  most  probable  Neocomian  ancestor.  The  supposed  relations  of 
some  of  the  genera  to  Stolicskaia  are  discussed  under  the  head  of  PulcheUia. 
The  parallelism  between  some  of  these  forms  of  Pidchellia  and  the  Hoplitidse 
is  so  close  that  it  requires  the  evidence  of  their  younger  stages  for  their 
separation.  It  is  closer  than  between  this  genus  and  any  one  of  the  Heinz- 
iidfe,  because  of  the  presence  of  the  line  of  double  elongated  tubercles  in 
the  latter. 

«The  Pulchelliidfe  were  not  mentioned  in  my  Cephalopod  chapter  in  Zittel's  Text-book,  owing  to 
the  accidental  omiss^ion  in  copying  of  a  page  of  the  manuscript. 


138  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

NICKLESIA  n.  gen.  Hyatt. 

This  genus  has  a  prolonged  smooth  stage,  followed  by  a  costated  stage, 
in  which  the  costaj  are  without  tubercles  and  cross  the  more  or  less  rounded 
convex  venter  without  becoming'  concave.  In  some  species,  as  in  the  type 
[iV.  dumasiana],  the  venter  does  not  become  decidedly  flattened  at  any 
stage  and  the  costae  are  very  slightly  developed.  The  following  species, 
described  and  fully  figui'ed  by  Nicklfes  in  his  Pal^ontologie  du  sud-est 
de  rEspagne,"  can  be  referred  to  this  section  of  the  genus:  Nick,  molfoi, 
levyi,  nolani,  lapparenti. 

In  other  species  the  venter  becomes  markedly  flattened  during  the 
latter  jjart  of  the  smooth  stage,  and  the  following  species,  described  b}'  the 
same  author,  are  referable  to  thi.s  section:  Nich.  zeilleri,  malladce,  hertrandi. 

NiCKLESIA   ALICANTENSIS  n.  sp.  Hyatt. 

Pulchellia  {Stol.  ?)  pulcheHa  Nickles,  1890,  M6m.  Soc.  geol.  France,  Paleontologie, 
No.  -4,  p.  13,  pi.  1,  figs.  10,  11. 

This  differs  from  d'Orbigny's  species  in  having  regularly  dichotomous, 
more  or  less  sigmoidal  costse,  a  wider  umbilicus,  less  compressed  form,  and 
broader  venter. 

The  following  species  can  also  be  included  under  this  head:  Kick, 
karsteni  (Uhlig)''  (j^ulchellus  of  Karsten). 

NiCKLEsIA    LENTICULATA    n.  sp.  Hyatt. 

Pulchellia  aff.  pulchdia  Gerhardt,  1897,  Neues  Jahrb.  fiir  Min.,  Geol..  und  Pal.,  Beil.- 
Bd.  XI,  p.  151:,  pi.  3,  fig.  9. 

D'Orbigny's  species  has  several  short  costse  between  the  longer  ones, 
and  the  internal  sections  between  the  longer  costations  are  smooth,  whereas 
in  both  of  the  above  the  costse  are  crowded  together  and  cover  the  sides  df 
the  shells. 

NiCKLESIA  DiDAYANA   (d'Orbigny). 

Nick,  didaijana  (d'Orbigny),  another  species  of  this  group,  has  been 
often  misapplied  to  species  having  channels  on  the  venter  and  lateral 
tubercles. 

"M^m.  Soc.  g^ol.  France,  Paleontologie,  Xo.  4,  1890. 

'i  Wemsdorfer  Schichten,  Denkschr.  K.  Akad.  Wiss.,  Wien,  Vol.  XLVI,  1883. 


PCLCHELLIID.E.  139 

NiCKLESiA  DUMASiANA  (d'Orbiguy). 

PI.  XVII,  figs.  6-S. 

Ammomtes  dimiasiamts  d'Orbiguy.  1S42,  Voyage  dans  rAmerique  meridionale.  Vol. 
m,  p.  69,  pi.  17. 

This  .species  is  fully  figured  by  d'Orbigny,  aud  easily  recognizable  in 
case  of  large  specimens.  The  French  specimens  that  usually  bear  this  name 
have  been  retained  here  with  a  question  mark.  The  three  examples  that 
are  in  the  Museum  of  Compai-ative  Zoology  are  much  smaller  than  the 
figures  of  the  South  American  species,  but  are  otherwise  identical,  and  there 
are  no  young  forms  of  the  latter  for  comparison.  The  young  specimen 
figured  shows  the  development  of  the  generic  costse  directly  from  a  form 
with  a  rounded  venter,  without  the  intervention  of  a  flat  or  concave  venter. 

Localitij:  Colombia, -South  America;  Escragnolles,  France. 

Age:  Neocomian. 

SUBPULCHELLIA  n.  gen.  Hyatt. 

This  becomes  a  distinct  generic  group,  consistently  with  the  principles 
advocated  in  this  and  other  papers,  because  it  represents  a  distinct  grade  in 
the  evolution  of  the  Pulchelliidit.  Its  permanent  adult  characteristics  cor- 
respond to  those  of  the  transient  condition  of  the  neanic  stage  in  the  young 
of  PiilcheUia.  Suhjndchellia  oehlerti  (Nickles)  has  a  smooth  involute  shell, 
with  a  concave  ventral  area  bordered  by  two  ridges.  The  venter  on  casts 
is  usually  flat  and  has  no  definite  ridges. 

The  genus  includes   also  Siihp.  fouqiiei  (Nickles),  and  Subp.  sauvacjeaui 

(Nickles.) 

Suhp.  sauvageaui  (Sayn)  has  lol)es  and  saddles  quite  difterent  from  the 
Spanish  form  as  figured  by  Nickles,  but  whether  it  or  Nicklfes's  species 
is  identical  witli  Hermite's  it  is  not  possible  to  state.  Hermite's  original 
description  and  figure  give  no  sutures.  The  shell  as  described  in  correction 
of  the  figure."  has  shght  costations,  present  also  in  Sayn's,  as  described  but 
not  as  figured,  and  not  mentioned  at  all  in  Nicklfes's  description.  The 
sutures  of  Nicklfes's  specimens,  one  from  near  Constantine,  Africa,  and  the 
other  from  Spain,  are  similar,  but  entirely  distinct  from  those  of  Sayn's 
figure.     Until  the  suture  of  Hermite's  original  or  of  a  specimen  from  the 

«Hermite,  Etudes  g^ol.  sur  les  lies  Bal^ares,  V^ol.  I,  1879,  p.  315,  pi.  4,  figs.  4,  5. 


140        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

same  locality  has  been  investigated,  it  can  not  be  stated  whether  Sayn's  or 
NickR's's  species  are  really  the  same  as  Hermite's.  In  these  smooth  forms 
the  shells  can  not  be  relied  on  to  show  specific  differences. 

SUBPULCHELLIA    CASTELLANENSIS    n.   sp.   Hyatt. 

PI.  XVII.  tigs.  1-5. 

The  two  specimens  in  the  ^Museum  of  Comparative  Zoology  here 
described  as  the  types  of  the  genus  and  species  are  both  smooth,  compressed, 
highly  involute  shells  similar  to  sauvageaui  and  others  in  aspect,  l)ut  with 
denticulations  on  the  auxiliary  saddles  not  found  in  those  species.  The 
largest  specimen  is  a  cast  28  mm.  in  whole  diameter,  probably  when 
complete  about  40  nmi.  The  inner  edge  of  the  living  chamber  shows  on 
one  side  and  this  was  about  one-half  of  a  volution  in  length.  The  suture 
figured  was  taken  from  the  oldest  stage  of  this  specimen.  The  venter  in 
this  cast  is  plano-convex,  and  there  are  ridges  on  the  ventro-lateral  angles, 
but  these  are  ridges  because  the  lateral  zones  are  faintly  concave, 
consequently  they  are  ridge-like  toward  the  lateral  aspects  and  not  on  the 
venter.  The  center  of  the  venter  has  a  raised  line  or  pseudo-keel  such  as 
is  figured  by  Sayn  in  his  Pul.  sauvageaui,  and  is  not  uncommon  in  species 
of  Placenticeras.  When  the  shell  is  present  the  venter  is  slightly  concave 
and  it  has  the  usual  ventro-lateral  ridges.  The  specimen  figured  (PI.  XVII, 
figs.  1-4)  is  somewhat  younger,  but  shows  a  partially  completed  living 
chamber  a  little  longer  than  one-half  of  a  volution. 

Locality:  Castellanes,  France. 

Age:  Neocomian. 

PULCHELLIA  Uhlig. 

Uhlig  designated  three  groups  when  he  described  this  genus,  the 
so-called  bicarinated  or  true  PulchelUa,  the  group  with  costte  crossing 
the  venter,  equa:!  to  my  Nkklesia,  and  those  with  a  keel  on  the  venter, 
the  equivalents  of  the  genus  Psihtissotia.  Nicklfes  recapitulates  these  facts 
and  the  observations  of  Douville,  and  joins  him  in  referring  the  firet  group  to 
PulchelUa,  and  also  in  thinking  it  possible  that  P.  piilchella  and  some  others 
may  be  referred  to  Stoliczkaia.  Nickltjs,  however,  retains  these  forms  under 
the  general  name  PulchelUa,  and  places  the  other  generic  names  in  brackets. 


PULCHELLIID^.  141 

He  has  also  traced  some  differences  between  the  sutures  of  the  different 
groups,  but  these  are  of  such  a  nature  that  one  does  not  get  clear  impressions 
from  drawings,  although  those  of  Nicklfes  are  remarkable  for  their  excellence 
and  full  of  instructive  details.  I  unfortunately  can  not  agree  with  tliese 
gentlemen  with  regard  to  Stoliczkaia. 

Xeumayr"  states  "  sehe  ich  mich  genotliigt,  eine  Gattuug  fiir  eine 
merkwiirdige  kleine  Gruppe  von  Ammoneen  aufzustellen,  namlich,  fiir  die 
eigeutiimlichen  Fonnen  der  indischen  Kreide,  welche  Stoliczka  *  *  * 
beschrieben  und  mit  den  Hallstatter  Arcesten  verglichen  hat."  He  then 
goes  on  to  establish  new  names  for  the  two  Indian  species  considered  by 
him  to  be  distinct  from  Ammonites  (lispar  d'Orbigny,  and  the  first  of  these, 
Stoliczkaia  tetragona  Neumayr  or  Amm.  dispar  Stoliczka,''  thus  becomes  the 
type  of  this  genus.  D'Orbigny's  figure  and  description  of  Amm.  dispar 
shows  a  compressed  involute  shell  with  a  volution  in  section  like  that  of 
NicMesia  pulchella  (d'Orbigny),  but  the  costa?  are  narrow,  and  although 
they  cross  the  venter  they  are  quite  distinct  from  those  of  this  family. 
D'Orbigny's  species  is  an  old  shell  of  some  other  group,  but  is  related 
neither  to  Pulchellia  nor  StoUczhaia. 

Sfol.  tetragona  has  a  quadragonal  volution  in  section  when  full  grown, 
venter  depressed  and  slightly  convex,  sides  same,  umbilical  zone  abrupt  and 
narrow.  Eibs  very  prominent  and  sharp,  reaching  across  the  venter  and 
side  and  having  alternating  shorter  costse  across  the  venter.  Only  one  row 
of  tubercles  along  the  A-entro-lateral  angles  in  the  young  until  in  the  neanic 
stage.  These  disappear  in  the  adult.  This  is  precisely  the  form  and  gen- 
eral aspect  of  some  of  the  Mantelliceratida?.  For  example,  Amm. 
mantelli  is  either  a  member  of  this  genus  or  a  very  similar  parallel  form. 
But  none  of  these  have  cost*  or  ornaments  or  channels  like  those  of 
Mantelliceratidse.  Probabl}-  also  the  young  are  more  or  less  distinct  in 
development. 

\Miether  this  last  be  true  or  not,  the  agreements  of  the  adult  sutures 
are  not  close  enough  to  place  such  widely  different  structured  shells  as 
Stol.  tetragona,  and  Pulchellia  piulclieUa  in  the  same  group,  especially  when 
there  is  close  agreement  between  the  latter  and  the  younger  stages  of  the 
typical  P.  compressissima  and  the  suture  lines  are  also  similar. 

oZeitschr.  Deutsch. geol.  Gesell.,  Vol.  XXVII,  1875,  p. 931. 
6  Foss.  Ceph.  Cret.  Southern  India,  pi.  4.5,  f.  2. 


142        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

The  keeled  smooth  forms  were  also  referred  by  Douville'  and  Nicklfes 
and  by  myself  in  Cephalopods  of  Zittel's  Text-book  under  the  name  of 
Psilotissotia  to  Tissotidse,  but  I  am  now  satisfied  that  this  is  an  erroneous 
view  of  their  true  affinities,  and  they  are  here  retained  in  the  Pulchelliidae. 

PULCHELLIA    NICKLESI    U.   sp.   Hyatt, 

Pxdchdlia  compressisslma  Nickles,  1S90,   Mem.  Soc.   ifeol.  France,  Paleontologie, 
No.  i,  p.  8,  pis.  1  and  3. 

This  species  is  now,  thanks  to  the  drawings  and  descriptions  of  Nickles, 
sufficiently  well  known  so  far  as  the  neanic  and  ephebic  stages  are  con- 
cerned, and  it  is  not  venturesome  to  say  that  in  the  still  younger  stages 
the  venter  must  have  been  I'ouuded  and  smooth  like  that  of  the  group  here 
named  Psilopukhellia.  The  true  P.  compressissima  d'Orbignv  is  a  much 
thinner  shell,  with  broader  costs?  and  narrower  venter,  the  costal  folds  on 
the  venter  narrower  and  less  deeply  channeled.  Doubtless  the  3'oung  are 
correspondingly  distinct.  The  umbilicus  is  also  narrower.  PidcheUia  sclilum- 
hergeri  Nicklfes,  Mdra.  Soc.  g^ol.  France,  Pale'ontologie,  No.  4,  p.  38,  pis.  7 
and  8 ;  Pul.  Columbiana  (compressissima  Gerhardt),  also  figured  by  d'Orbiguy 
as  the  young  of  his  Amm.  gahatus  in  the  Voyage  dans  I'Amerique  merid- 
ionale,  Pul.  selecta,  and  Pul.  hettneri  also  belong  to  this  genus. 

Age:  Barremian. 

There  are  two  species  described  from  Djebel-Ouach  by  Sayn,  Pul. 
changarnieri  Sayn  and  Pul.  kiliani  n.  sp.  (P«Z.  (Heinzia)  ouachensis,  Sayn," 
pars).  This  last  is  distinct  from  Heinzia  ouachensis  Sayn  in  not  having  an 
inner  line  of.  tubercles  and  in  its  naiTOwer  ventral  channels  as  well  as  in  its 
sutures  as  described  by  Sayn. 

PuLCHELLiA  coMPRESSissiMA  (d'Orbiguy). 

PI.  XVII,  figs.  9-12. 

Ammonites  compressissimiw  d'Orbigny,  1840,  Terr.  Cretace,  pi.  61. 

This  species  is  vei-y  peculiar  and  altogether  distinct  from  the  forms 
usually  placed  under  the  same  name  by  authors  generally.  D'Orbigny's 
figure  is  very  similar  to  a  specimen  of  the  Krantz  collection  from  Escra- 
gnolles,  the  same  locality  as  the  shell  figured  by  d'Orbiguy.  The  form  of 
this  cast  is  quite  as  much  compressed  and  involute,  the  costae  are  present 

"Ann.  Soc.  d' Agriculture  de  Lyon,  6th  series,  Vol.  Ill,  1890,  j).  15.5,  jil.  2,  fijr.  15,  not  fig.  14. 


PULCHELLIID.E.  143 

onlv  on  the  outer  half  of  the  sides,  the  spaces  between  are  narrow  sulcations 
that  cross  the  venter.  The  costse  cross  the  venter  with  undiminished 
breadth  and  are  channeled,  but  this  channel  is  so  shallow  that  I  at  first 
thought  this  must  be  the  young  of  another  species  with  very  broad  costaa, 
Amm.  catiUus  d'Orbigny.  The  specimen  described  is  just  a  little  older  than 
the  shell  figured  as  compressissimus  by  d'Orbigny  and  ribs  begin  suddenly  to 
bend  forward  on  the  last  part  of  the  outer  volution.  Amm.  catillus  d'Orbigny 
may  also  belong  to  this  genus,  but  the  characters  of  the  young,  which  alone 
can  determine  this  question,  are  not  known. 

Locality:  Escragnolles,  France. 

Age:  Neocomiau. 

PSILOTTSSOTIA  Hyatt. 

This  genus  was  unluckily  considered  by  me  when  mentioned  for  the 
first  time  "  as  a  member  of  the  Tissotiida^.  In  this  I  was  not  led  by  the 
opinions  of  Douvill^  and  Nicklfes,  but  by  what  I  then  considered  to  be  its 
true  atfinities.  It  has  become  obvious  in  studying  Faratissotia,  which 
approaches  it  nearest  in  form  and  in  agreement  of  the  development,  that 
this  is  not  a  natural  association.  Nicklfes's  plates  also  show  that  the  sutures 
are  similar  to  those  of  true  Pulchelliidne.  They  are  involute  forms,  smooth, 
and  compressed  in  the  earlier  stages  and  having  at  this  time  or  all  through 
the  neanic  stage  a  smooth  keel  that  may  in  older  stages  become  tubercu- 
lated.  Costse  may  be  represented  by  fine  folds  as  in  Psil.  mariolcs  Nicklfes, 
until  a  late  age,  but  when  they  do  appear  they  are  heavy,  fold-like,  and 
sigmoidal.  In  this  species  also  a  median  lateral  line  of  nodes  ajjpears.  If 
their  real  affinities  are  with  this  family,  as  they  certainly  appear  to  be  now, 
they  can  be  accounted  for  as  direct  derivations  of  FsilojndchelUa  which  has 
evolved  a  keel.  The  intermediate  aspect  of  species  like  Pul.  defforgesi  and 
haugi  indicates  that  the  shell  did  not  have  a  flat  ventral  area  at  any  stage, 
but  was  the  direct  outcome  of  the  evolution  of  Psilopidchellia. 

This  includes  besides  the  type,  Psil.  chalmasi  (Nickles),  the  following 
species:  Psil.  mariolfs,  defforgesi,  reigi,  haugi,  Nicklfes;  Pul.  de forges/  Nickles 
is  described  by  liim  as  having  simply  a  sharp  venter,  but  its  aftinity  with 
mariolae  would  bring  it  into  the  group  and  the  sharp  venter  may  be 
merely  due  to  the  age  of  the  example  figured. 

oZittel's  Text-book,  p.  590. 


144  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

LOPHOLOBITES  Hyatt. 

LOPHOLOBITES    COTTEAUI    (Nickles). 

Neolohites  ?  cotteaui  Nickles,  1890,  Mem.  Soc.  geol.  France,  Paleontologie,  No.  4. 

p.  54,  figs.  36,  37;  pi.  5,  fig.  9. 
LophoJoh'des  cotteaui  H^yatt,  1900.  Ceph.     Zittel's  Text-book  Pal.,  p.  590. 

This  is  a  small,  very  involute,  compressed,  smooth  form,  with  minute 
umbilicus  and  subacute  venter.  The  external  characteristics  and  sutures 
indicate  this  to  be  a  retrogressive  but  more  involute  shell,  allied  to  such 
species  as  Psilotissotia  haw/i,  figured  on  the  same  plate  by  Nickles.  The 
sutures  are  entirely  distinct  from  those  of  Neolohites,  especially  in  the  bifid 
character  of  the  first  lateral  saddles  and  the  greater  differentiation  of  the 
inner  saddles  and  lobes,  which  are  more  distinct  from  those  of  the  outer 
part  of  the  same  sutures  than  in  Neolohites.  All  of  these  discrepancies 
can  be  accounted  for  on  the  supposition  that  this  is  a  retrograde  form  of 
Ptilchellia.  This  also  accounts  for  its  small  size  when  nearly  outgrown,  as 
in  this  specimen.  Nickles  recognized  the  great  differences  between  this 
shell  and  Neolohites,  but  hesitated  to  describe  it  as  a  diff"erent  genus  because 
of  the  great  difference  in  its  size.  This  fear  was  unfounded,  since  Neolohites 
could  not  have  had  a  similar  set  of  sutures  at  any  age. 

Age:  Barremian. 

KNEMICERATIDiE. 

The  external  aspect  of  the  species  of  this  group  ]ilaces  them  apparently 
close  to  the  Buchiceratidse,  but  the  sutures  and  the  absence  of  a  keel  at  all 
stages  separate  them  widely.  The  first  lateral  saddles  exhibit  tendencies 
to  division  into  several  distinct  branches,  as  in  the  Engonoceratida^,  and 
the  outlines  of  the  other  saddles  and  lobes  also  are  similar.  The  division 
of  the  first  lateral  saddles  is  not  earned  so  far  as  it  is  in  Engonoceratidsie. 
The  principal  first  lateral  resulting  from  the  secondary  division  of  the 
primitive  first  lateral  is  consequently  a  broad  solid  saddle  instead  of  the 
narrow  first  lateral  of  that  family. 

Unluckily,  the  dorsal  sutures  were  in  no  case  exposed,  and  the 
conditions  of  fossilization  in  every  specimen  made  excavation  im])racticable. 

The  forms,  both  by  their  ornamentation  and  general  development, 
are  apparently  more  specialized  and  more  complex  than  those  of  the 
Engonoceratidae,  and  although  the  young  was  seen  in  only  one  example  in 
a  section  the  appearances  were  the  same  as  in  sections  of  species  of  the 


KNEMICERATID^E.  145 

Engonoceratidae.  It  has  been  therefore  assumed  that  they  had  a  similar 
stage  in  which  the  venter  was  concave  and  liad  continuous  ridges  on  the 
veutro-lateral  ang-les. 

KNEMICERAS   Bohm." 

There  are  but  two  Hnes  of  nodes  on  the  sides  and  straight  broad  costte, 
bifurcating  between  them.  The  venter  is  broad  and  concave,  the  costa? 
and  nodes  are  opposite,  and  the  venter  is  often  transversely  ridged  between 
the  nodes.  The  ventral  lobes  have  the  same  shape  as  in  Bmhkeras  and 
Boemeroceras  and  have  similar  truncated  siphonal  saddles.  The  ornamenta- 
tion and  form  resemble  these  genera,  but  there  is  no  keel  at  any  age  and 
the  development  is  quite  distinct.  The  young  are  not  compressed  as  in 
Buchiceras,  and  the  ventral  zone  is  concave  in  an  early  neanic  substage  and 
remains  concave  throughout  life.  This  .shows  similarity  to  Engonoceras  and 
Placeuficeras.  The  lateral  lobes  and  saddles  are  similar  to  those  of  Engono- 
ceras, but  the  inner  laterals  are  fewer  in  number  and  the  tirst  lateral  saddle.- 
are  more  complicated.  The  divisions  of  the  first  may  be  counted  as  four 
or  even  five  lateral  saddles  derived  from  a  primitive  first  lateral.  Until 
some  one  ontogeny  is  studied  the  correct  enumeration  can  not  be  given. 

The  young  were  seen  in  section.  The  rounded  venter  of  the  nepionic 
stage  is  succeeded  in  the  neanic  stage  by  a  flat-ventered  volution  with  quad- 
ragonal  outline,  and  the  concave  venter  appears  in  the  earliest  part  of  the 
ephebic  stage.  At  this  time  the  venter  is  ^-ery  broad,  the  sides  flat  and 
obviously  costated  and  tuberculated  on  the  umbilical  shoulders.  Whether 
there  were  tubercles  on  the  edges  of  the  venter  was  not  determinable. 

At  an  early  neanic  substage  the  umbilicus  was  open,  the  venter  flat 
and  broad,  but  narrower  than  the  dorsal  diameter  through  the  umbilical 
shoulders,  the  lateral  zones  flat  and  convergent,  the  umbilical  zones  well 
developed.  These  characters  and  the  broad  costis  and  nodes  of  the  later 
stages  and  the  venter  are  similar  to  those  of  Pulchelliida;,  but  the  division 
of  the  first  lateral  saddles  in  full-grown  specimens  and  other  sutural 
characters  are  dissimilar.  The  species  ^discovered  in  the  Cenomanian  of 
Portugal  appears  to  indicate  that  the  real  age  of  the  fossils  found  at  Mount 
Lebanon  is  Cenomanian,  although,  as  may  be  seen  by  the  context,  I  have 
doubts  whether  any  of  the  latter  belong  to  the  fauna  of  the  rocks  in  which 
they  have  been  found. 

a  Zeitschr.  Deutsch.  geol.  Gesell.,  Vol.  L,  1898,  p.  200. 
MOX   XLH^— 03 10 


146        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Knemiceras  sykiacum  (von  Buch). 

PI.  XVI,  rigs.  -i-S. 

Amm.  syriaciis  von  Buch,  Abhandl.  K.  Akad.  Wiss.  zu  Berlin,  1848,  pi.  ti. 
Kni'inkenis  syriaciun  Bohm,  1898,  Zeitschr.  Deutsiih.  gcol.  Gesell..  Vol.  L,  p.  200. 

Von  Buch's  iig'ures  of  this  species  on  liis  pi.  6  are  excellent  in  all 
characters,  but  his  suture  line  on  pi.  7  is  either  erroneous  or  belongs  to 
another  form. 

One  gerontic  specimen  is  about  o.5  mm.  in  whole  diameter,  with  living 
chamber  nearly  one-half  of  a  volution  in  length.  A  smaller  specimen,  45 
mm.  in  diameter,  has  also  reached  into  an  extreme  gerontic  substage  and 
has  living  chamber  of  same  length.  Von  Buch's  specimen,  according  to 
his  figures,  was  also  in  gerontic  stage,  but  evidently  somewhat  larger, 
perhaps  70  mm.,  or  thereabouts,  when  living  chamber  was  present. 

This  stage  is  indicated  in  one  .specimen  as  in  von  Buch's  figure  by  the 
approximation  of  septa  in  pairs  as  if  the  individual  were  only  temporarily 
affected  by  weakness  and  then  resumed  the  usual  rate  of  increase.  In  one 
specimen  the  last  sutures  are  irregularly  spaced.  The  last  three  next  to 
the  living  chamber  are  approximate.  A  slightly  greater  interval  occurs 
between  these,  and  there  is  a  pair  closely  approximated,  and  apicad  of  this 
is  a  broader  chamber  and  again  a  pair  of  approximated  sutures.  Apicad  of 
this  last  pair  there  is  a  chamber  broad  on  the  venter  but  so  naiTow  near  the 
lines  of  involution  that  the  sutures  are  crowded  together  on  the  umbilical 
shoulder.  Apicad  of  this  is  the  ephebic  stage,  with  all  sutures  regularly 
spaced.  The  gerontic  sutures  are  not  always  so  iiTegular,  and  there  may 
be  as  many  as  eight  sutures  showing  more  or  less  inequalit}^  in  spacing, 
ending  with  a  series  gradually  becoming  closer  and  eventually  overlapping. 
The  whole  duration  of  the  gerontic  stage,  including  the  living  chamber, 
consists  of  about  three-fourths  of  a  volution.  The  lobes  and  saddles  become 
shorter  and  the  outlines  simpler  in  this  stage.  Temporary  approximation 
of  sutures  occurs  often  in  the  growth  of  these  shells,  and  it  is  not  always  a 
sign  that  the  gerontic  stage  has  been  reached,  but  when  it  is  continued  for 
some  time,  as  in  von  Buch's  figure,  and  after  a  period  of  prolonged  regu- 
larity in  the  width  of  the  living  chambers,  it  is  obviously  due  to  senility. 
There  are  no  signs  of  a  row  of  tubercles  on  the  median  aspect  of  the  sides, 
and  there  are  obviously  only  two  rows  of  nodes  with  heavy  fold-like  bifurcated 
costiB  between. 


KNEMICERATID.E.  147 

The  nodes  continue  to  increase  in  length  and  size  throug-hoixt  hfe  initil 
in  the  latter  half  of  the  gerontic  living  chamber,  when  tliey  show  a  decided 
and  rapid  decrease  on  the  venter  but  persistently  increase  on  the  umbilical 
shoulders  until  near  the  end  of  this  chamber.  The  living  chamber  was 
incomplete  on  the  venter  in  all  of  these  specimens,  although  in  several  it 
was  complete  near  the  umbilicus  and  somewhat  over  one-fourth  of  a  volution 
in  length. 

The  first  lateral  saddles  are  bifid,  having  two  broad  arms,  and  both  of 
these  are  again  faintly  bifurcated,  these  subdivisions  being  minutely 
denticulated  on  the  edges  in  perfectly  unworn  sutures,  which  can  be  found 
best  by  removing  encrusting  ostreans.  In  some  specimens  the  second 
lateral  saddle  does  not  split  up  completely  from  the  first,  and  instead  of 
three  principal  lateral  saddles  there  are  but  two,  as  shown  in  PI.  XVI,  fig.  5. 
In  others  the  division  is  complete,  as  it  probably  is  in  the  later  stage  of  the 
specimen  shown  in  PI.  XVI,  fig.  8.  No  specimen  so  far  seen  carries  out 
the  complete  division  of  the  remaining  first  lateral,  although  in  some  the 
median  marginal  lobe  is  quite  long.  It  is  a  curious  fact  that  all  of  these 
specimens — eleven  in  number  and  collected  from  five  difterent  sources — 
should  have  encrusting  bryozoa  and  ostreans  on  the  exterior  of  the  cast  and 
all  more  or  less  worn  on  all  other  parts  of  the  surface.  The  lobes  and 
saddles  nowhere  exhibit,  and  it  is  not  likely  that  this  species  ever  exhibited, 
the  peculiar  lobes  and  saddles  figured  by  von  Buch  on  his  pi.  7.  The 
entire  suture  seems  to  be  incorrect  for  this  species,  whereas  those  given 
in  pi.  6  are  right  so  far  as  they  go,  althougli  taken  from  the  usual 
worn  surfaces,  of  casts.  Bohm's  figure,  (pioted  below,  is  accurate,  but 
belongs  to  an  older  stage  than  that  figured  in  tliis  work.  The 
second  and  sixth  lateral  saddles  are  bifid,  the  seventh  and  eighth  broad, 
flattened,  and  entire.  There  are  marks  upon  unworn  sutures  indicating  the 
presence  of  slight  denticles  on  the  edges  of  the  principal  saddles,  but  no 
such  divisions  and  prominent  marginals  as  in  von  Buch's  figure,  pi.  7.  The 
ventral  lobe  has  two  arms  as  in  Entjonocems ;  the  dividing  siphonal  saddle  is 
api^arently  flat,  but  when  clearly  defined  it  lias  a  diminishing  base  divided 
by  a  minute  siphonal  lobe.  Faint  denticulations  are  present  on  both  this 
saddle  and  the  sides  of  the  arms  of  the  ventral  lobe.  The  lateral  lobes  are 
club  shaped,  denticulated  on  the  top,  but  entire  on  the  sides  near  their 
base  between  the  phylliform  bases  of  the  saddle.     There  are  irregular  trifid 


148        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

outlines  such  as  appear  in  Bohm's  figure,"  but  there  are  also  regular  trifid 
bases  to  the  first  lateral  saddles.  The  former  arise  from  the  iiregular 
growth  of  the  marginal  saddles  of  the  first  or  outer  (originallj-  bifid)  arm 
of  the  first  lateral  saddle,  making  sometimes  a  simple  triple  division,  and 
sometimes  this  outer  arm  itself  becomes  trifid,  equally  or  more  or  less 
unequally,  as  in  Bohm's  figure.  The  variation  of  the  sutures  is  very 
considerable  in  this  species,  but  there  seems  to  be,  so  far  as  my  material 
reaches,  no  sufficient  gi-ounds  for  the  separation  of  specimens  having  trifid 
first  lateral  saddles  from  those  having  this  part  bifid.  In  fact  one 
specimen  shows  early  in  the  ephebic  stage  a  bifid  first  lateral  on  one  side 
and  a  trifid  saddle  on  the  other  side  of  the  venter,  i.  e.,  the  tAvo  arms 
of  the  first  lateral  on  one  side  are  regularly  bifid  and  on  the  other  the 
inner  arm  is  trifid  and  the  outer  arm  bifid.  Occasionally  this  outer  arm 
may  have  four  marginals.  In  one  specimen  the  inner  arm  is  bifid  and  the 
outer  arm  has  three  minute  marginals.  In  one  specimen  again  (PI.  XVI, 
fig.  5)  there  are  three  arms,  each  regularly  subdivided  b}'  a  median 
marginal  lobe.  This  saddle  can  perhaps  be  best  described  in  general 
terms  as  having  three  arms  derived  from  an  original  bifid  form  and 
usually  preserving  a  record  of  this  original  form  in  the  shortness  of  the 
outer  marginal  lobe  as  compared  with  the  second  marginal  and  also  in 
the  usually  bifid  outline  of  the  base  of  the  third  or  innermost  arm.  Often, 
as  in  PI.  XVI,  fig.  8,  the  inner  arm  is  sufficiently  separated  to  be  counted 
as  a  second  latei'al  saddle. 

The  specimen  described  by  Hamlin  in  Syrian  Fossils''  is  fine  only  on 
one  side  and  the  supposed  shell  "the  thin  test  almost  entire"  does  not 
exist.  Handin  was  misled  by  the  smooth  surface  and  the  presence  of  a 
thin  brown  layer.  That  this  is  not  the  shell  is  shown  by  the  sutures, 
which  are  somewhat  worn,  not  showing-  the  denticulations  plainly.  The 
living  chamber  is  obviously  neai'ly  complete  and  is  a  trifle  less  than 
one-half  of  a  volution  in  length.  I  have  examined  twenty-two  specimens 
of  this  species  and  not  a  single  one  had  even  fragments  of  the  shell 
preserved  and  many  were  incrusted  with  ostreans  and  bryozoa.  There  is 
no  positive  proof  that  these  ammonites  were  liA'ing-  members  of  the  fauna 
in  which  they  were  found,  but  there  are  obvious  reasons  in   their  aspect 

o  Ueber  Amin.  pedernalis:  Zeitsch.  Deutsch.  geol.  Gesell.,  Vol.  L,  1898,  p.  199. 
6  Mem.  Mus.  Comp.  Zool.,  Vol.  X,  No.  3,  1884,  p.  11. 


KNEMICERATlDaE.  149 

anil  ill  the  presence  of  these  incrusting  growths  on  the  casts  for  consid- 
ering them  as  having  been  fossil  casts  when  the  incrusting  animals  grew 
upon  them. 

Locality:  Mount  Lebanon,  Syria. 

Age:  Cenomanian. 

Knemiceras  compressum  11.  s]).  Hyatt. 

PI.  XVI,  figs.  9,  10,  1.5-18. 
Ammonites  vihrayecmus  HaraHn,  ISSi,  Mem.  Mus.  Comp.  Zool.,  Vol.  X,  No.  3,  p.  12. 

The  typical  form  of  this  species  is  sejiarable  from  the  variety 
suhcompressum  in  full-grown  specimens  by  the  greater  compression  of  the 
volutions,  narrower  venter,  and  less  development  of  the  nodes  on  the 
umbilical  shoulders.  The  proportionate  increase  by  growth  of  the  ventro- 
dorsal diameters  is  also  greater  with  relation  to  the  transverse  than  in  the 
stouter  variety  described  below,  and  in  all  these  respects  it  differs  still  more 
from  Kneni.  sijriacimi.  The  shell,  however,  until  45  to  50  mm.  in  diameter 
is  not  distinguishable  from  the  shell  of  that  species.  As  stated  by  Fraas  and 
Hamlin,  the  sutures  in  the  worn  casts  are  similar  to  syriacHiii,  but  in  a  large 
specimen  of  the  same  size  as  the.  type  of  this  species  (PI.  XVI,  fig.  15)  in 
the  Museum  of  Comparati\e  Zoology  these  are  less  worn  than  usual  and 
full  grown.  These  sutures  (PI.  XVI,  figs.  17,  18)  show  the  large  ventral 
lobes,  which  occupy  iiearl}^  the  entire  breadth  of  the  venter  instead  of  only 
the  central  part,  as  in  the  stouter  variety  and  in  syriacuni.  The  lateral 
saddles  and  lobes  are  very  long  and  narrow  and  the  bases  of  the  saddles 
swollen,  rounded,  and  phylliform,  resembling  those  of  Sphenodiscus.  The 
apical  ends  of  the  saddles  are  also  similarly  shaped,  broad,  denticulated, 
and  cutting  deeply  into  tlie  saddles.  In  the  gerontic  stage  the  lobes  and 
saddles  become  shorter  again,  as  in  the  younger  stages,  and  more  like  those 
of  si/riacum.  The  most  perfect  cast  (PI.  XVI,  figs.  15,  16)  is  70  mm.  in 
diameter,  without  living  oliamber,  the  outer  volution  38  mm.,  the  umbilicus 
10  mm.,  and  same  volution  opposite  22  mm.,  the  thickness  of  the  last  being 
13  mm.  between  costae. 

The  largest  specimen  is  from  Beirut,  No.  10902G  in  the  collection  of 
Columbia  University.  This  has  no  living  chamber,  and  the  actual 
diameter  is  85  mm.,  estimated  diameter  about  90  mm.  Diameter  when 
living   chamber  was  present  could    not    have    been    less    than    130    mm. 


150        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Sutures  are  considerably  worn,  except  in  one  place  at  diameter  of  75  ram., 
the  volution  being  23  mm.  ventro-dorsal  diameter.  These  were  similar  to 
those  of  the  tvpical  specimens,  except  the  hrst  lateral  saddles,  whicli  were 
narrower  and  distinctly  bifid;  the  innermost  inflections  were  not  seen. 

The  nodes  were  present  on  the  umbilical  shoulders,  but  apparently 
disappear  on  the  last  half  of  the  outer  volution,  but  this  could  not  be 
proved  on  account  of  the  state  of  this  fossil. 

The  venter  remained  concave  to  the  end.  The  ventral  tubercles 
became,  however,  much  finer  and  more  closely  set  than  in  the  ephebic 
stage,  and  I  should  think  more  perfect  specimens  might  show  the 
correlative  disappeaiance  or  obsolescence  of  the  costations.  I  doubt  if  the 
costse  are  ever  so  broad  in  this  species  as  in  syriacum.  The  state  of  these 
fossil  casts  tends  to  confirm  the  opinion  that  they  were  not  living  members 
of  tlie  fauna  with  which  they  were  found. 

Out  of  the  eight  casts  in  the  Museum  of  Comparative  Zoology  only 
three  were  suitable  for  observation,  and  all  of  the  three  more  or  less 
imperfect,  and  there  was  not  even  the  minutest  piece  of  a  shell  on  any  of 
them.  The  same  is  also  true  of  the  large  .specimen  from  the  collection  of 
Columbia  University. 

Knemiceras  compbessum  var.  subcompre.ssum  Hyatt. 
PI.  XVI.  %s.  11-1-U  19. 

Amm.  iiyriacus  (pars)  voii   Buch,   Abhandl.   K.   Acad.   Wiss.    zu   Berlin,   1S4S    (not 

tigured). 
Amm.  syriacus  (pars)  Conrad,  Lynch's  Exp.  Dead  Sea  and  Jordan,  1852,  pi.  li,  fig. 

7-1,  two  upper  figures  (not  fig.  6). 

This  variety  has  heretofore  been  confounded  with  Knem.  syriacuni, 
from  which  it  is,  however,  easily  separated.  The  form  even  in  extreme  age 
is  more  compressed,  the  nodes  on  the  umbilical  shoulders  are  not  so  promi- 
nent, and  the  venter  and  transverse  diameters  do  not  broaden  out  in  the 
later  ephebic  and  gerontic  substages,  as  in  that  species;  the  nodes  also  on 
the  edges  of  the  venter  are  longer  and  narrower  than  in  that  species.  The 
sutures  are  verv  similar  in  these  two  forms. 

A  specimen  from  Mukhtara,  Syria,  in  tlie  American  Museum  of 
Natural  History,  New  York,  reaches  97  mm.  diameter  without  living  cham- 
ber, and  shows  that  the  shell  sometimes  reaches  a  larger  size  than  115  mm. 
in  diameter. 


KNEMICERATID^.  151 

A  specimen  in  the  Museum  of  Comparative  Zoology  is  50  mm.  in 
diameter.  This  retained  its  flatter  sides  and  proportionally  broad  venter  to 
the  end  of  the  last  volution.  The  living  chamber  is  incomplete  and 
somewhat  less  than  half  of  a  volution  in  length.  A  specimen  from  Abeih, 
Mount  Lebanon,  in  the  Museum  of  Comparative  Zoology,  53  mm.  in  diam- 
eter, has  a  living  chamber  obviously  very  nearly  complete  and  somewhat 
less  than  half  a  volution  in  length.  This  is  therefore  approximately  the 
length  of  this  part.  One  of  the  specimens  in  the  Krantz  collection  in  the 
Museum  of  Comparative  Zoology  shows  thick  shell  on  venter  where  it  has 
been  covered  and  protected  by  outer  volution.  Outside  of  this  the  cast  is 
worn  more  or  less,  and  there  are  absoluteh-  no  remnants  of  shell  under  the 
encnisting  ostreans  that  occur  on  the  exposed  parts.  The  condition,  in 
other  words,  proves  that  this  and  probably  other  fossils  mentioned  above 
were  not  living  members  of  the  Syrian  fauna  as  heretofore  described,  but 
came  from  some  earlier  epoch  and  were  already  in  the  condition  of  fossil 
casts  when  the  in  crusting  ostreans  grew  upon  them. 

Locality:  Gilead  Mountains  east  of  Jordan,  Mount  Lebanon,  Syria. 

Age:  Cenomanian 

Knemiceras  attenuatum  (Hyatt). 
Pi.  XVII,  figs.  13-15. 

BiicMceras  attenuatum  Hyatt,  1875,  Proc.  Boston  Soc.  Nat.  Hist..  Vol.  XVII,  p.  372. 
Glottoceras  attmuatum  Hyatt,  ibid,  note. 

The  sutures  agree  quite  closely  with  those  of  Knemiceras  compressum, 
but  the  alternating  tubercles  on  the  edges  of  the  venter  and  the  form  of 
this  part  are  essentially  Engonoceran. 

The  original  specimen  is  65  mm.  in  diameter;  it  is  a  cast  without  any 
vestiges  of  the  shell.  The  ventral  lobe  is  deep  and  narrow  and  like  that  of 
Knemiceras  The  first  lateral  saddle  is  also  Knemiceran  in  outline.  It  is 
unequally  divided  into  three  parts.  The  outer  arm  is  trifid,  but  with  such 
slight  marginals  that  they  are  merely  sinuosities.  The  central  part  is  a 
minute  saddle,  and  the  inner  has  a  trilid  base.  The  second  lateral  is 
phylliform  and  so  faintl}-  bifid  that  I  was  not  sure  of  the  fact.  All  the 
remaining  saddles  are  subphylliform,  with  broad  bases  and  symmetrically 
bifid,  except  the  seventh  and  eighth,  the  la.st  on  the  line  of  involution. 
These  are  entire.  The  first  to  the  sixth  lobes  are  simple  and  denticulated; 
the  seventh  and  eighth  are  entire. 


152        FSEUDOCEKATITES  OF  THE  CRETACEOUS. 

This  species  was  named  erroneously  Glottoceras  in  a  note  quoted  above 
and  accidentally  left  uncorrected  in  the  proof. 

The  great  regularity  of  the  outlines  of  the  bifid  saddles  and  the  small 
dividing  marginal  lobes  are  probably  characteristic,  as  well  as  the  fineness 
and  number  of  the  tubercles  of  the  outer  lines  and  the  presence  of  a  third 
line  beginning,  apparently,  on  the  latter  part  of  the  outer  volution. 

Localitij :  Celendin,  Peru. 

Age:  Cenomanian? 

Knemiceras  gabbi  n.  sp.  Hyatt. 
PI.  XVIII,  figs.  1-3. 

Ammonites  attemuitus  Gabb,  1877,  Jour.  Acad.  Nat.  Sci.  Philadelphia,  2d  series,  Vol. 
VIII.  p.  264.  pi.  36,  fig.  1  a  and  I. 

The  originals  of  Gabb's  figures  have  not  been  found  in  the  collections 
of  the  Academy  of  Sciences  of  Philadelphia  and  I  could  not  obtain  them 
for  comparison,  but  the  suture  line  figured  by  Gabb  is  distinct  from  that 
given  on  PI.  XVII  of  this  work,  and  Gabb's  form  is  much  stouter  at  tlie 
same  age,  has  larger  nodes  and  a  broader  venter.  The  old  age  with  a 
rounded  broad  venter  is  probably  not  particularly  distinctive,  although  it 
may  perhaps  be  that  this  change  never  occurs  to  such  excess  in  true 
attennafum  as  it  does  in  gabbi. 

Locality:  Quebrada  de  Huari,  Peru. 

Age:  Cenomanian? 

Knemiceras  uhligi  (Choflfat). 

Placenticeras  uhligi  Choffat,  1898,  Faune  Cret.  du  Portugal,  Vol.  I,  2d  series,  pp.  4 
and  77,  pi.  2,  figs.  3-5;  pi.  i,  fig.  2;  and  pi.  22,  figs.  ■14-46. 

This  is  a  compressed  species  similar  to  Kn.  compressum,  but  differing  in 
the  sutures.  The  saddles  are  very  broad  and  have  flat  bases  with  more 
denticulations.  The  lobe's  are  more  like  those  of  compression,  but  the  inner 
ones  are  quite  diff'erent.  The  marginal  divisions  are  less  complete  than  in 
coinpressuiit. 

Locality:   Portugal. 

Age:   Lower  Bellasian  (Cenomanian.) 


DESCRIPTIONS  OF  SPECIES.  153 

ENGONOCERATID^. 

Shells  apt  to  be  involute.  The  venter  is  concave  and  is  occupied  for 
its  entire  breadth  by  a  smooth  zone.  The  sutures  are  variable  in  the  dift'erent 
genera  and  approximate  in  some  forms  to  those  of  Sphenodiscus.  There  is 
a  similar  tendency  in  most  of  the  species  to  have  broad  saddles  with 
plndliform  bases,  which  are  either  entire  or  bifid,  while  the  lobes  have 
narrow  bases  and  are  more  or  less  expanded  apicad  and  apt  to  have  trifid 
ternnnations.  The  simplicity  and  shortness  of  the  saddles  and  lobes  is 
correlated  with  the  tendency  to  produce  a  much  larger  number  of 
inflections  and  great  variability  in  the  outlines  in  the  same  species  and 
sometimes  even  on  different  sides  of  the  same  specimen.  The  ventral  lobes 
are  short,  spreading  apically,  and  ha\'e  usually  pointed  short  and  entire 
siphonal  saddles. 

PR0TP:N C40N0CERAS  Hyatt. 

The  ephebic  form  is  compressed  and  involute,  as  in  Engonoceras  and 
Metenyonoceras  of  the  same  subfamily  group,  and  it  is  also  similar  to  the 
ueanic  stages  of  Engonoceras,  Sphenodiscus,  and  Placenticeras. 

The  shell  is  smootli,  except  in  the  gerontic  stage,  where  folds  appear. 
The  venter  is  moderately  broad  and  decidedly  concave,  bordered  by  sharp, 
smooth  ridges.  These  are  exactly  the  external  characters  of  the  young 
during  neanic  stages  of  the  species  of  the  different  genera  mentioned. 

The  sutiires  have  the  same  ventral  lobes  as  in  Engonoceras  and 
Metengonoceras,  and  similar  lateral  sutures,  but  the  saddles  are  %'ery  broad 
and  short  and  the  lobes  have  fewer  marginals. 

Type,  Prof,  gahhi  (Bohm),  Whitney  collection,  in  Museum  of  Com- 
parative Zoology. 

The  septa  follow  internally  the  curvatures  of  the  sutures,  concave 
along  the  mesal  plane  and  convex  only  on  the  areas  on  each  side  of  the 
zone  of  involution. 

PrOTENGONOCERAS   GAB15I    (Bohm). 

PI.  XVII,  tigs.  16-20. 

Ammonites  pedfirnal is  (ja}')h,  1869,  Pal.  California,  Vol.  II,  pi.  35,  figs.  1,  la. 
Engonoceras  (julhlV>b\xm,  1698,  Zeitschr.  Deutsoh.  geol.  Ge^ell.,  Vol.  L,  p.  197. 

A  cast  of  one-half  of  a  volution  in  Museum  of  Comparative  Zoology 
from  Professor  Whitney  shows  ephebic  stage.     The  wiiole  diameter,  partly 


154        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

estimated,  is  69.5  mm.,  the  outer  portion  of  this  vohitiou,  partly  estimated, 
is  42.5  mm.,  the  umbiUcus  is  5  mm.  and  the  opposite  i)art  of  same  volution  is 
22  mm.  The  shell  is  present  on  the  venter  but  not  on  the  line  of  involu- 
tion. Greatest  transverse  diameter  of  outer  volution  is  25  mm.,  the  iimer 
part  is  11  mm.,  both  through  the  umbilical  shoulders,  shell  on  one  side  and 
not  on  the  other  side.  Probably  shell  would  have  made  the  difference  of 
5  mm.  in  eacli  case. 

This  is  a  compressed  shell,  closely  similar  in  aspect  to  Enr/onoceras 
nddcm  and  the  ephebic  smootli  stag-e  of  Protengonoceras  F  emarginatum,  but 
the  involution  is  greater;  the  costations  in  this  stage  are  fainter,  but  can  be 
plainly  enough  seen  both  on  cast  and  on  the  shell  in  a  cross  light.  Thev 
are  less  than  in  Gabb's  figure,  but  the  form  of  venter  and  aspect  of  shell, 
including  amount  of  involution,  shows  that  we  are  dealing  with  Gabb's' 
species.  There  are  also  no  tubercles  on  the  umbilical  shoulders.  The  first 
large  fold  is  partly  present  on  the  broken  edge  of  the  outer  volution  in 
the  small  fragment  figured,  showing  the  beginning  of  the  gerontic  stage. 
The  venter  is  decidedly  concave  with  slight  ridges  on  either  side.  This 
form  of  venter  is  found  in  the  neanic  stage  and  the  whorls,  although 
stouter,  are  similarly  compressed  when  the  whole  diameter  is  onlv  13  mm. 
At  diameter  of  +4  mm.  this  venter,  although  almost  as  broad  as  the  trans- 
verse diameter,  is  alreadv  like  that  of  the  adult,  but  may  be  a  little  flatter. 

Other  details  could  not  be  seen.  It  is  obvious  that  the  young  acquire 
the  concavity  and  sharp  lateral  ridges  of  the  ventei'  in  an  early  neanic 
substage  at  a  time  when  the  volution  becomes  flattened  on  the  lateral 
zones.  The  form  is  then  obviously  like  some  stouter  and  less  involute 
forms  of  this  genus  not  yet  discovered. 

The  sutures  are  very  slightly  flexed  apicad;  the  saddles  and  lobes 
closely  similar  to  those  of  Metengonoceras. 

The  venter  is  slightly  asymmetrical;  the  first  pair  of  saddles  on  the 
riglit  are  divided  by  a  very  slight  marginal  lobe.  There  are  nine  saddles 
and  eight  lobes  on  the  right  side,  the  seventh  saddle  alone  being  bifid. 
The  marginal  lobe  dividing  this  saddle  appears  on  the  earliest  suture  of 
this  volution.  Lobes  on  the  left  side  of  a  more  advanced  stage  show  that 
this  simplicity  is  due  to  age. 

A  larger  specimen,  same  locality,  in  the  gerontic  stage,  is  108.5  mm.  in 
diameter  and  has  the  shell  preserved.     Outer  part  is  57.5  mm.,  umbilicus 


ENGONOCERATID.E.  155 

7.5  nan.,  and  opposite  side  same  volution  46.5  nun.,  no  shell  present.  The 
greatest  transverse  diameter  of  the  volution  is  30  mm.,  and  of  thesmaller 
part  opposite  is  22  nun. 

The  shell  is  marked  by  bands  of  growth  and  fold-like  obscure  costse 
wliicli  appear  in  the  gerontic  stage.  These  terminate  at  the  umbilical 
shoulders,  and  along  the  centran  surface  of  tlie  lateral  aspect  have  very 
broad  swellings  and  then  subside  into  the  flat  general  surface  toward  the 
periphery.  The  venter  is  slightly  broader  than  in  the  ephebic  stage  above 
described  and  the  volution  stouter,  owing  to  the  development  of  lateral 
swellings  and  the  slight  decrease  in  the  involution  due  to  old  age.  The 
umbilical  shoulders  and  the  umbilical  zones  are  abrupt  instead  of  being 
rounded  and  sloping  as  in  the  adults.  The  living  chamber  is  complete 
near  the  line  of  involution  and  is  about  one-half  of  a  volution  long 
internallv  and  apparently  about  the  same  externally  when  restored.  The 
concavit}-  of  the  venter  is  maintained  for  one-half  of  the  length  of  the 
living  chamber.  Beyond  this  it  could  not  be  followed,  but  there  are  some 
indications  of  the  possible  rounding  of  the  venter  in  extreme  age. 

The  sutures  are  cpiite  distinct  from  those  of  the  ephebic  stage  in  the 
s})ecimen  above  described.  There  were  eight  saddles  and  seven  lobes  to  the 
umbilical  shoulders,  remainder  on  the  umbilical  zones  being  concealed. 
The  interesting  fact,  however,  can  be  noted  that  in  this  gerontic  stage  new 
saddles  and  lobes  were  not  added  as  the  sides  broadened.  The  increase  of 
the  sides  was  met  by  the  broadening  out  of  the  saddles.  The  first  laterals 
were  very  broad,  the  second  and  third  had  not  changed  much,  but  Ijegin- 
niug  with  tlie  fourth  they  became  irregularl}-  broader  toward  the  vimbilicus, 
and  the  seventh  was  6  mm.  in  breadth,  whereas  the  sixth  lobe  was  only 
about  1  mm.  long.  The  lobes  remained  about  the  same  as  in  the  adult 
stage. 

The  form  of  the  volutions,  smc»oth  concave  venter,  slightly  costated 
sides,  with  large  folds  only  in  gerontic  stage,  and  primitive  sutures  all  show 
that  this  is  a  species  like  the  similar  stag-es  in  the  development  of  tuberculated 
forms  in  Metengonoceras  and  also  similar  to  the  young  of  Placenticeras.  It 
is,  however,  a  deeply  involute  shell  and  is  not  therefore  by  an)'  means  the 
most  primitive  form  of  its  own  subseries.  It  indicates  the  existence  of  a 
distinct  subseries  having  similar  smooth  concave  venters  and  less  involute 
or  more  discoidal  shells,  which  in  the  gerontic  stage  become  stouter  with 


156        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

gibbous  sides  and  have  also  comparatively  flattened  or  rounded  and  much 
wider  venters. 

Having-  been  loaned  through  the  kindness  of  Dr.  Pilsbry  another  sjjeci- 
mon  of  this  species  from  the  collection  of  the  Academy  of  Sciences,  Phila- 
delphia (PI.  XVII,  fig.  20),  I  can  state  the  following  additional  particulars: 
The  diameter  is  about  82  mm.,  partly  estimated.  The  living  chamber  is 
one-half  of  a  volution  in  length  on  the  periphery,  but  is  much  shorter  on 
the  line  of  involution,  owing  to  the  great  apical  trend  of  the  aperture.  This 
has  a  broad  but  very  slight  sinus  on  either  side  and  apparently  no  lateral 
crests  on  the  sides  that  could  be  separated  from  the  rostrum.  This  last, 
however,  was  broken  and  could  not  be  decisively  determined.  The 
specimen  is  in  its  gerontic  stage  and  upon  the  inner  parts  of  each  side  has 
four  heavy  folds  which  disappear  near  the  venter.  The  bifidity  of  the 
internal  saddles  is  variable,  since  in  another  specimen  in  the  collection  ot 
the  Museum  of  Comparative  Zoology  the  sixth  saddles  were  bifid. 

Locality:  Arivechi,  Sonora,  Mexico. 

Age:  Fredericksburg  group,  Comanche  series. 

Protengonoceras  planum  n.  sp.  Hyatt. 

PI.  XVIII,  tig-s.  H-9. 

This  species  is  described  from  a  fragment  which  would  be  ordinarily 
insuificient  for  diagnostic  work.  The  greatest  length  of  this  piece  is  only 
22.5  mm.,  the  ventro-dorsal  diameter  of  the  volution  14  nnn.,  the  greatest 
diameter  at  umbilical  shoulders  5.5  mm.  Nevertheless,  the  cast  is  perfectly 
smooth,  the  sides  flat,  and  the  venter,  which  is  only  1  mm.  in  width,  is  also 
smooth,  concave,  and  bicarinate.  These  characteristics,  especially  the 
attenuated  venter  and  smooth  sides,  distinguish  it  quite  sufilciently  from  the 
preceding  species  to  justify  specific  separation,  lliere  are  ten  saddles,  all 
narrow,  the  first  symmetrically  bifurcated,  as  in  other  forms  of  this  genus 
and  Engonoceras.  They  are  entire  and  from  second  to  eighth  more  or  less 
club  shaped,  but  the  ninth  is  broader  and  bifid.  The  tenth  and  eleventh 
are  entire,  occupying  the  umbilical  zone.  The  dorsal  zone  of  impression 
has  six  saddles,  counting  the  outermost  one  above  m,eutioned  (PL  XVIII, 
fig.  9).  There  are  ten  narrow  zygous  external  lobes  (PI.  XVIII,  fig.  8)  on 
the  right  side.  The  first  is  club  shaped  and  entire,  the  second  to  the  fifth 
similar,  but  faintly  trifid.     The  sixth  to  the  tenth  are  shorter  and  decrease 


ENGONOCERATID^.  157 

iu  length  to  the  Hue  of  involution  and  are  entire.  Ou  the  opposite  or  left 
side  there  are  ten  saddles  and  eleven  lobes.  The  tenth  saddle  is  completed, 
and  there  is  a  small  lobe  on  the  line  of  involution.  The  first  saddle  is 
narrower  and  the  eighth  and  ninth  saddles  broad,  and  both  similar  to  the 
ninth  on  the  right  side  in  being  bifid.  On  both  sides  the  first  five  lobes 
are  long,  and  the  same  change  occurs  in  the  shortness  of  the  sixth  and 
remaining  lobes  and  saddles.  The  matrix  is  similar  to  that  which  occurs  in 
the  Colorado  formation  at  Horton's  mill,  Dallas  County,  Tex. 

Locality:  Texas. 

Age:  Stanton  suggests  Upper  Cretaceous  from  the  matrix. 

Protengonoceras  ?  EMARGINATUM  (Cragiu)." 

Sphenodisciis  emarginatus  f  Cragin.  1S93,  Geol.  Surv.  Texas.  Fourth  Ami.  Rept., 
p.  245. 

This  species  is  described  as  having  straight  distinct  ventral  channel  at 
the  diameter  of  90  mm.  and  also  as  having  two  rows  of  feeble  tubercles,  one 
on  the  umbilical  shoulders  and  the  other  midway  on  the  lateral  aspect. 
The  bilobed  saddles  mentioned  by  Cragin  indicate  a  more  complicated 
suture  line  than  occurs  in  Protengonoceras  as  far  as  known,  but  the  condition 
of  the  venter  indicates  that  genus. 

Not  having  seen  any  specimens  of  the  species,  I  can  not  say  positively 
that  it  is  a  member  of  this  genus. 

LocaJitij :  2  miles  south  of  Pleasant  Point,  Tex. 

Age:  Comanche  series.  Walnut  beds. 

ENGONOCERAS  Neumayr. 

Although  the  descriptions  and  figures  of  Engonoceras  pierdenale  led  me 
to  believe  that  this  species  had  an  acute  venter,  Bohm''  has  stated,  after 
studying  the  fragraentar}-  originals,  that  these  had  truncated  concave  venters, 
bordered  bv  ventro-lateral  ridges  or  elongated  tubercles,  and  that  the  species 
upon  which  the  genus  Engonoceras  was  founded,  Amm.  pierdenalis  v.  Buch, 
closely  resembles  his  Eng  stolleyi.  The  two  fragments  figured  by  Bohm  do 
not  show  conclusively  that  this  is  the  fact,  but  it  appears  to  be  safest  to 
follow  him  in  the  eff'ort  to  give  stability  to  von  Buch's  name  and  Neumayr's 
geims.     Von  Buch's  and  Roemer's  descriptions  lead  to  the  belief  that  the 

0  See  p.  177,  where  this  species  is  referred  to  Engonocenis. — T.  W.  S. 

^Ueber  Ammonites  pedernalis  v.  Buch:  Zeitschr.  Deutsch.  geol.  Gesell.,  Vol.  L,  1898,  p.  183. 


158        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

shell  casts  they  described  had  acute  venters,  but  this  is  probably  an  en-or. 
In  studying  this  group  of  fossils  such  a  mistake  is  easily  made,  owing  to  the 
simplicity  of  the  sutures,  the  narrowness  of  the  flattened  venters,  and  smooth- 
ness and  symmetrical  aspect  of  the  fossils,  although  considerably  worn  and 
altered  by  abrasion. 

The  presence  of  three  distinct  lines  of  nodes,  the  flatness  and  nodose 
edges  of  the  venter  throughout  the  earlier  and  ephebic  stages,  the  broad  and 
often  zigzag  outline  of  the  venter  in  the  geroutic  stage,  caused  by  the  extra 
development  of  the  outer  line  of  alternating  nodes,  enable  one  to  separate  the 
species  of  this  genus  readily  from  those  of  Metengonoceras,  notwithstanding 
the  close  similarity  of  the  sutures.  The  young  during  the  neanic  stage  are 
compressed,  involute,  and  smooth,  with  concave  venter  and  form  like  Pro- 
tengonoceras.  Von  Buch  and  Neumayr  both  describe  the  principal  saddles 
of  Engonoceras  pierdenale  as  bifid,  and  this  occurs  in  the  species  here  sup- 
posed to  represent  Engonoceras,  but  does  not  occur,  so  far  as  known,  in 
Meteugonoceras.  All  specimens  so  far  seen  have  been  casts,  either  entireh' 
naked  or  with  only  the  nacreous  layer  partly  preserved. 

The  attention  of  collectors  is  called  to  the  fact  that  some  of  the  species 
bear  no  convincing  marks  of  having  been  autochthonous  members  of  the 
faunas  in  which  they  are  habitually  found. 

This  genus  differs  from  Neolohites  only  in  having  denticulated  lobes,  if 
the  figures  of  tlie  sutures  heretofore  given  correctly  represent  their  outlines. 

Engonoceras  belviderense  (Cragin). 
PI.  XVIII,  figs.  4,  5. 

Ammonites  belvideremis  Cragin,  1894,  1895,  Am.  Geol.,  Vol.  XIV,  pi.  1.  tigs.  3-5; 

Vol.  XVI,  p.  .369. 
BucMceras  {Sphmodlscnif:)   helmidereiim  Cragiu,  1900,  Colorado  Coll.   Studies,  Vol. 

Vm,  p.  27. 

Through  the  kindness  of  Professor  Cragin  I  have  seen  some  specimens 
of  this  species,  and  one  of  these  has  been  given  in  the  figure.  This  alone 
was  not  much  crushed,  but  the  sutures  could  not  be  made  out.  The  aspect 
is  similar  to  that  of  Eng.  uddeni,  but  the  sides  and  venter  ai-e  flatter  and 
smoother.  There  are  similar  nodes  on  the  umbilical  shoulders  and  those  on 
the  edges  are  alternate;  there  are  nascent  folds  on  the  outer  part  of  the 
aides.     It  reaches  a  larger  size  than  other  forms  before  it  begins  to  acquire 


ENGONOCERATID^E.  159 

the  usual  gerontic  characters — that  is,  before  the  venter  becomes  convex 
and  more  or  less  zigzag-  in  outline.  The  type  of  Cragin's  species  is  the 
small  specimen  referred  to  above.  This  has  sutures  with  numerous  small 
saddles  closely  set  on  the  suture  line,  and,  so  far  as  could  be  seen,  one  of 
Cragin's  fossils  of  the  same  lot  with  that  figured  had  similar  sutures. 
Cragin  describes  this  species  as  having  a  row  of  tubercles  that  mav  be 
developed  on  the  inner  ends  of  the  low  folds  or  costpe  occupying  the  outer 
half  of  the  sides.  There  are  some  very  obscure  signs  of  the  existence  of 
such  markings  in  these  fossils  also.  These  are  doubtful  even  to  the  touch 
and  are  not  visible  to  the  eye.  This  may  be  owing  to  the  condition  of  the 
fossils. 

Locality:  Belvidere,  Kans. 

Age:  Champion  bed  and  Kiowa  shales,  probably  near  base  of 
Washita  Comanche  series,  Lower  Cretaceous. 

Engonoceras  uddeni  (Cragin). 

PI.  XIX,  tigs.  !-•). 

Sphenodiscus  helviderensis  var.   uddeni  Cragin,  190t),  Colorado  Coll.  Studies,  Vol. 
VIII,  p.  30.  pi.  1,  tigs.  3,  4. 

A  fragmentary  cast  in  iron  pyrite,  No.  23147  U.  8.  National  Museum, 
PI.  XIX,  fig.  4,  5,  shows  a  few  of  the  last  sutures  and  a  portion  of  the 
living  chamber.  The  diameter,  partly  estimated,  is  about  82  mm.,  the 
outer  volution  is  44  mm.,  the  undiiHcns  8  mm.,  the  same  volution  opposite 
from  line  of  involution  to  venter  30  mm.,  no  shell  being  jj resent.  The 
form  is  compressed  and  highly  involute,  l)ut  slightly  stouter  than  in  the 
more  compressed  eman/inatum.  There  is  only  one  line  of  nodes,  those  on 
the  iimbilical  shoulders.  The  costte  are  fine,  and  like  elevated  bands  of 
growth  gathered  to  a  focus  at  these  nodes.  They  are  sigmoidal  with  single 
fine  lines  between  the  nodes,  externally  more  pronounced  folds  appearing 
in  the  later  gerontic  substage,  but  no  nodes  are  present  on  this  jiart  in  this 
specimen.  The  venter  is  flattened  until  near  tlie  last  part  of  the  living 
chamber,  which  is  distorted  through  compression. 

The  part  of  the  living  chamber  preserved  indicates  that  it  was  not  less 
than  half  a  volution  on  the  umbilical  side.  The  ten  lobes  and  eleven 
saddles  on  both  sides  are  very  similar  in  outline  to  those  of  emarginatHm. 
The  seventh  and  eighth  lobes  on  l^otli  sides  are  bifid. 


1(30  psp:udoceratites  of  the  cretaceous. 

The  ventral  and  also  the  fii'st  lateral  saddle  are  asymmetrical.  These 
have  the  usual  form  but  are  ratlier  narrow.  The  internal  parts  of  the 
sutures  are  deflected  orad  toward  the  umbilical  shoulders  so  that  they  rise 
materially,  giving  them  a  pecular  aspect  in  this  s])ecimen.  The  lobes  are 
similar  to  those  of  emnrgmatum,  but  are  narrower  and  shorter  and  the  saddles 
broader,  and  shorter  in  proportion.  The  second  to  the  sixth  saddles  are 
entire,  the  seventh  to  the  ninth  bifid,  and  tlie  tenth  saddle  is  on  the  line  of 
involution.  The  sutures  are  the  same  on  both  sides  of  this  specimen.  The 
lobes  are  irregularly  bifid. 

There  is  a  frag-ment  of   a  larger  size  consisting  of  one-fourth  of  a 

o  i^  o 

volution  with  stouter  proportions,  labeled  "Locality  1490  U.  S.  Geological 
Survey,  north  of  Pottsboro,  Tex.,  Upper  Comanche  (GraysonJ,"  that  may 
belong  to  the  same  species,  Ijut  the  sutures  and  aspect  are  distinct  enough 
to  belong  to  a  diff'erent  species." 

The  inner  line  of  large  nodes  and  the  median  lateral  are  present,  Ijut 
no  outer  line,  and  there  are  similar  distinct  costations. 

The  venter  has  a  similar  outline  also,  but  the  specimen  being  larger 
and  older,  the  venter  is  more  rounded. 

The  sutures  are  similar,  except  that  the  inner  arm  of  the  first  lateral 
saddle  is  much  narrower  and  entire,  the  outer  arm  is  distinctly  bifid,  making 
the  whole  outline  approximately  trifid,  the  remaining  saddles  are  longer  and 
distinctlv  phylliform  as  in  SpJieiiocUseus,  and  the  lobes  are  correspondingly 
Ijroader  apically  as  in  that  genus.  These  effects  may  perhaps  be  due  to 
the  greater  age  of  the  specimen.  There  is  apparently  the  same  immber  of 
lobes  and  saddles.  There  are  nine  saddles  visible  on  the  broken  end,  right 
side,  and  there  may  be  one  more,  making  ten  saddles  and  nine  lobes. 

A  fragment  obtained  from  Dr.  F.  A.  Udden,  locality  northeast  of  Little 
River  station.  Rice  County,  Kans.,  is  the  original  specimen  used  by  Cragin 
and  is  figured  below  on  PI.  XIX.  It  is  in  fine  state  of  preservation,  being 
fossilized  with  iron  pyrite.  The  breadth  of  the  side  is  53  mm.,  the  greatest 
transverse  diameter  is  at  about  one-third  of  the  bi'eadth  from  the  line  of 
involution  and  is  20.5  mm.  The  venter  is  very  narrow,  about  3  nun.  in  1  jreadth ; 
it  has  no  obvious  nodes,  but,  as  in  the  type,  faint  undulations  may  be  felt  with 
the  finger  on  the  ventro-lateral  angles.  The  sutures  are  quite  different,  but 
have  the  same  general  character.  The  first  lateral  saddles  are  quite 
distinct    on  the   two  sides,  owing  to  the  asymmetry  of  the  ventral  lobe. 

"Figured  as  Engonoceras  retardum  n.  s|i.  Hyatt,  PI.  XV,  figs.  15-17. 


ENGONOCERATID.E.  161 

The  sixth  saddle  on  the  left  side  is  bifid;  the  seventh  is  broad  and 
STmmetrically  and  deeply  bifid,  looking  like  two  entire  saddles;  the  eighth 
has  a  large,  slightly  bifid,  onter  and  a  tongue-shajjed  innei'  arm ;  the  tenth 
is  bifid.  The  ninth  and  tenth  can  be  reckoned  in  several  difierent  ways  on 
account  of  the  peculiar  forniation  of  the  lobes,  either  as  above,  or  tlie  inner 
arm  of  the  ninth  be  called  the  tenth  and  what  is  here  named  the  tenth  can 
be  classed  as  the  eleventh,  or,  on  account  of  shortness  of  the  lobes,  the 
whole  may  be  considered  as  a  single  broad  saddle  with  three  arms,  the 
outer  and  inner  arms  bifid  and  central  arm  narrow  and  entire.  The 
eleventh  saddle  is  trifid  and  broad,  ihe  twelfth  and  thirteenth  entire,  and 
the  last  is  on  the  line  of  involution.  On  the  right  side  the  first  lateral 
saddles,  on  account  of  the  asymmetry  of  the  ventral  lobe,  are  narrower  and 
the  second  is  much  reduced.  The  second  to  the  seventh  are  entire,  the 
eisrhth  and  ninth  are  svmmetricallv  bifid,  the  tenth  to  the  thirteenth  are 
entire.  The  twelfth  and  thirteenth  saddles  alone  correspond  or  are 
symmetrical,  bilateral  on  both  sides  of  the  body.  The  lobes  have  a  ten- 
denc}'  to  become  irregular  at  their  terminations  and  are  long  and  narrow 
on  both  sides  and  more  alike  than  the  saddles. 

There  is  also  a  large  fragment  of  an  example  of  this  species  in  its 
"erontic  stag'e,  or  of  an  undescribed  soecies,  associated  on  same  mount 
with  E.  snhjecfum  (No.  10756  Collection  Boston  Society  Natural  History). 
The  diameter  from  line  of  involution  toward  venter  as  far  as  fragment 
goes  is  68  mm.  There  are  only  a  few  millimeters  wanting  externally, 
since  part  of  the  first  saddle  is  present.  There  are  apparently  nine 
saddles  only  on  the  side,  all  entire  except  the  seventh,  eighth,  and  ninth, 
which  are  bifid.  The  first  to  fourth  lobes  are  long  and  narrow  and  the 
saddles  stout  but  phylliform.  These  sutures  belong  obviously  to  a  very 
aged  shell,  since  out  of  nine  sutures  visible  the  eighth  is  the  first  that  does 
not  slightly  overlap  and  the  last  four  overlap  2:)rogressively  more  and  more. 

The  absence  or  very  slight  development  of  the  outer  lines  of  nodes 
and  the  absence  of  distinct  ridges  on  the  ventro-lateral  edges  of  the  venter 
distinguish  this  species  from  E.  suhjedum.  The  sutures  of  these  two  run 
closely  together,  although  the  saddles  and  lobes  of  this  form  are  somewhat 
stouter  and  broader  at  tlie  same  age  than  in  E.  suhjectum. 

Locality:   McPherson  County,  Kans. 

Afje:  Comanche  series,  Kiowa  shales. 
MOX  XLIV — 03 11 


162        PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

Engonoceras  serpentinum  (Cragin). 
PI.  XIX,  tigs.  7-14;  PI.  XX,  figs.  1-5. 

Sj)/ienodtsciis  iehild^'ensia  var.   serpentinum  Ci'agin,   1900,   Colorado   Coll.    Studies, 
Vol.  VIII,  p.  31,  pi.  2,  figs.  4-6. 

Three  casts  of  this  species  (Loc.  No.  1489)  are  well  preserved  in  a 
matrix  of  hematite.  The  diameter  of  one  (1489  b)  is  58  mm.,  the  vohition 
is  29  mm.,  the  umbilicus  7  mm.;  the  same  volution  opposite,  measured 
from  lines  of  involution  to  venter,  22  mm.,  no  shell  being  present. 

The  involution  conveys  the  larger  part  of  each  outer  whorl,  but  the 
internal  volutions  are  plainly  visible  in  the  umbilicus  and  the  involution  is 
obviously  much  less  in  the  younger  stages  than  in  adults.  The  volutions 
are  much  compressed.  The  venter  is,  however,  flattened  and  slightl}'  con- 
cave in  the  ephebic  stage,  and  in  the  gerontic  stage  it  becomes  asymmetrical 
and  sinuous  through  the  development  of  the  large  tubercular  terminations 
of  the  alternating  costsK.  In  the  ephebic  stage  the  costse  are  sigmoidal  and 
only  slightly  developed;  in  the  gerontic  stage  these  become  broad  on  the 
outer  parts  with  an  external  and  internal  line  of  nodes,  and  become  obscure 
internally  or  umbilicad  of  the  second  row  of  nodes,  but  they  ai'e  obviously 
confluent  to  the  internal  or  third  line  of  smaller  nodes  on  the  umbilical 
shoulders.  These  nodes,  like  tlie  costse,  come  in  on  the  casts  at  a  late 
ephebic  substage,  the  side  of  the  yoimger  whorls  being  smooth.  The 
tubercles  of  the  outer  line  in  tlie  one  specimen  (1489  b)  are  sharper  and 
the  costse  at  the  points  convergent,  whereas  in  the  second  specimen  from 
the  same  locality  the  latter  broaden  out  and  the  tubercular  terminations 
are  more  elongated  This,  however,  resembles  those  of  the  other  specimen 
in  the  ephebic  and  anagerontic  substage,  the  marked  elongation  coming  in 
with  the  metagerontic  substage. 

A  similar  disposition  to  broadening  out  of  costa^  is  also  observed  in  the 
larger  specimens  in  extreme  age,  but  is  not  so  marked  and  the  venter  also 
remains  narrower.  The  living  chamber  is  not  complete,  but  it  must  have 
been  about  one-half  of  a  volution  in  length  on  the  line  of  involution.  Other 
specimens  show  the  same,  but  none  give  the  outer  margins.  The  inner 
lines  of  tubercles  remain  close  to  the  umbilical  shoulder,  receding  outwardly 
very  slightly  in  extreme  age. 


ENGONOCERATlDvE.  163 

The  variation  between  different  specimens  in  external  aspect  of  the 
casts  is  not  great  except  in  the  gerontic  stage  owing-  to  the  greater  or  less 
development  of  the  nodose  costations,  bnt  the  variations  in  the  sutures  are 
such  that  no  two  specimens  are  alike. 

The  fourth  suture  on  right  side  of  figured  specimen  has  eleven  lobes 
and  ten  saddles,  and  is  only  slightly  curved  apicad.  The  arms  of  the 
ventral  lobe  are  seen  cutting  deep  into  the  lateral  aspect.  The  inner 
branch  of  the  first  lateral  saddle  is  broad,  entire,  and  club-shaped,  as  are 
all  other  saddles,  except  the  ninth  and  tenth,  which  are  bifid.  The  deptli 
and  size  of  the  lobe  that  divides  what  is  here  assumed  to  be  the  first 
lateral  is  so  like  other  lobes  that  it  is  not  always  easy  to  determine  whether 
it  is  a  marginal  or  realU'  tlie  first  lateral  lobe.  The  lobes  are  all  clubbed; 
that  is,  narrow  orad  and  swelling-out  apicad,  and  from  first  to  seventh 
show  very  faint  digitations  or  indications  of  from  three  to  four  very  minute 
incipient  marginal  lobes,  the  fifth  sliowing  the  equal  and  the  remaindei-  tlie 
unequal  numbers  of  these. 

Specimen  1489a  has  short  lobes  and  corresponding  saddles  like  the 
above,  but  narrow  outer  branches  to  the  first  lateral  saddles  and  arms  of 
ventral  lobe  hardly  apparent  on  the  lateral  aspect.  There  are  eleven  lobes 
and  ten  saddles  easily  distinguishable,  i.  e.,  not  overlapping  and  similar  to 
those  of  the  first  specimen,  but  saddles  narrower  outwardly  and  broader 
inwardly,  and,  what  is  more  remarkable,  the  seventh,  ninth,  and  tenth  are 
bifid,  the  eighth,  which  is  bifid  in  the  first  specimen,  being  entire  in  this. 

Specimen  1489c  has  such  distinct  sutures  that  one  hesitates  to  place  it 
in  the  same  species  with  those  marked  1489a  and  1489b.  The  sutures  are 
more  deeply  curved  apicad,  the  outer  five  saddles  and  lobes  longer  and 
narrower,  and  the  inner  ones  broader  and  flatter.  There  are,  however, 
eleven  lobes  and  ten  saddles  visible,  as  in  the  otliers,  and  the  age  is  about 
the  same.  The  sutures  are,  however,  closely  approximated,  so  that  the 
lobes  slightly  overlap  even  in  the  ephebic  stage  and  form  columns  except 
along  the  lines  of  tlie  first  to  the  second.  The  ninth  saddle  alone  is  bifid, 
all  others  being  entire. 

The  discoidal  aspect  of  the  young  in  the  umbilicus  can  be  plainly 
seen  in  this  specimen.  The  sutures  on  the  left  side  have  the  same  general 
character,  but  differ  in  details  from  those  of  the  right  side.  The  outer 
saddles  are  alike,  but  the  inner  ones  are  narrow  and  more  numerous. 


164        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

The  fragments  from  Denison  consist  of  an  almost  entire  gerontic  living 
chamber  and  one  somewhat  more  imperfect  one  of  the  same  age,  a  smaller 
fragment  (tf  })art  of  ephebic  living-  chamber  and  last  suture.  This  last 
shows  that  in  the  ephebic  stage  the  venter  is  smooth,  narrow,  concave,  and 
has  no  tubercles,  but  is  bordered  by  two  smooth  ridges.  There  are  nine 
lobes  and  nine  saddles,  the  seventh  and  eighth  saddles  being  bifid.  The  line 
of  involution  is  occupied  by  a  minute  lobe,  as  it  is  also  in  other  specimens. 
There  are  five  dorsal  lobes  between  this  and  the  antisiphonal  lolje  on  each 
side.  The  first  dorsal  saddle  next  the  antisiphonal  is  entire,  the  second  and 
fifth  are  bifid,  the  rest  are  entire.  The  third  dorsal  lobe  was  l^ifid,  the 
remainder  on  both  sides  of  this  were  entire  and  nari'ower.  The  antisiphonal 
lolje  was  narrow  and  bifid.  The  sutures  of  an  early  ephebic  or  late  neanic 
substage  in  one  of  these  showed  that  the  notation  of  the  saddles  in  this 
group  is  correct,  and  that  the  first  lateral  has,  as  stated,  two  unequal  arms, 
the  inner  l)eing  really  an  adventitious  saddle  derived  from  the  inner  side 
of  the  first  lateral.  The  outer  saddles  and  lobes  are  similar  in  outline  to 
those  of  some  specimens  from  northeast  of  Gainesville,  but  tlie  inner  saddles 
and  lobes  are  shorter  and  broader. 

A  specimen  from  Denison,  kindly  lent  me  by  Prof.  F.  W.  Cragin  [is 
also  figured  and  is  probably  one  of  the  types  of  his  variet}*  serpentimis  now 
raised  to  specific  rank]. 

This  species  is  distinguishable  from  others  by  the  extremely  late  stage 
to  which  the  protengonoceran  venter — i.  e ,  the  concave  venter  bordered  by 
two  ridges — is  retained.  Practically  it  lasts  throughout  the  ephebic  stage, 
and  the  engonoceran  stage  is  passed  through  with  great  rapidity.  In  this 
the  venter  is  flat  and  bordered  by  well-defined  elongated  tubercles,  and 
consequently  there  is  a  quick  appearance  of  the  senile  stage  with  elevated 
convex  venter  between  large  elongated  nodes.  It  should  be  noticed  that 
one  of  the  varieties  imitates  the  sutures  of  E.  suhjertion  in  the  shape  of  the 
saddles  and  lobes,  but  these  remain  characteristically  simple  in  outline 
(PI.  XIX,  fig.  11).  Some  varieties  have  bifid  saddles  and  some  do  not  have 
them.  The  dividing  marginals  of  the  saddles  enlarge  by  growth  when  they 
occur,  until  the}-  often  form  lobes  practicalh'  inseparable  from  others. 

Local itij:  Four  and  one-half  miles  northeast  of  Gaines^alle  and 
Denison,  Tex. 

A(/e:   Upper  part  of  Comanche  series.  Paw  Paw  beds,  Washita  group. 


ENGONOCERATID^E.  165 

Engonoceras  pierdenale  (von  Buch). 

PI.  XX,  tigs.  6-13. 

AmmonUesj^lcrdemdls  von   Buch,  Ahhaiidl.  K.   Akad.  Wiss.  zu  Berlin,  1848,  pi.  H, 

tigs.  8-10. 
AMimm/'tex  Dedcrnalis  Roenier.  1852,  Kreideb.  v.  Texas,  PI.  I.  tig.  3. 
Engonocerax 2»^dei",aU><  Bohm.  ISKS.  Zeitsclir.  Deutsch.  geol.  Gesell.,  Vol.  L,  p.  183. 

I  have  placed  this  here  with  n  query,  because  I  find  it  impracticable  to 
identify  tlie  young-  figured  by  von  Buch  with  any  form  known  to  me. 
The  ventral  lobe  and  saddle  and  the  otlier  parts  of  tlie  suture  might  belong 
to  the  young  of  a  species  a  grade  more  complicated  than  any  here  described. 
There  is  a  row  of  elongated  nodes  close  to  the  venter  in  von  Buch's  figure, 
but  the  presence  of  such  ornaments  is  denied  in  the  text,  and  the  nodes  are 
said  to  be  on  one  side  and  due  to  the  exposure  of  the  joints  of  the  siphuncle. 
Roemer  states  that  he  had  the  originals  in  linud  when  making  his  descrip- 
tion, and  that  the  species  was  nuu-li  larger  than  that  described  by  him. 

Neumayr  mentioned  this  species  as  the  type  of  his  genus  Eiif/onoceras" 
and  repeats  the  name  "pierdenalis"  instead  of  "pedernalis,"  the  name  given 
by  Roemer,  and  also  repeats  von  Buch's  figure  of  the  suture  on  PI.  7  ot 

tJber  Ceratiten. 

Von  Buch  and  Neumayr  also  both  describe  the  principal  saddles  as 
bifid,  a  condition  that  does  not  exist  in  any  specimen  (if  the  genus  that  I 
have  seen. 

Localitij:  Texas. 

Age:   Fredericksburg  group  of  Comanche  series. 

Engonocekas  pierdenale  variety  commune  Hyatt. 

PI.  XXI.  tig.  1. 

A  fragment  in  U.  8.  National  Museum,  No.  8301b,  from  Bell  County, 

Tex.,  is  slightly  crushed  in  the  umbilical  region,  but  has  sutures  and  mark- 

ino-s  well  preserved.     At  larger  end  the  volution  is  33  by  14  mm.,  at  smaller 

end  24  by  1 1  nun. 

The  venter  is  flattened  and  narrow,  bordered  by  small  elongated 
tubercles  rather  numerous  and  closely  set  as  in  the  adults  of  this  species. 
There  is  an  inner  row  of  tubercles,  hardly  perceptible  median  row,  and 
equally  faint  fold-like  costations  on  the  outer  part  of  the  volution,  which 
can  be  felt  better  than  seen  on  this  cast. 

"Amm.  d.  Hilsbild.  Xorddeutschlands,  Palwontogr.,  Vol.  XXVIl,  1S80-81,  pp.  188,  141. 


166        PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

The  ventral  lobe  is  slightly  asj'mmetrical  to  the  left,  g-iviiig-  ri«e  to 
considerable  diflferences  in  the  first  lateral  saddles  on  either  side.  The  first 
lateral  on  the  rio-lit  is  l)ifid,  the  outer  arm  very  broad  and  Ijifid,  the  inner 
subdivided  asymmetrically  by  a  very  minute  mai-ginal  lobe.  Be}'ond  this 
the  inner  arm  is  entire  and  quite  large  and  iihylliform.  There  are  ten 
saddles  and  nine  lobes  on  this  side  All  tlu-  former  are  entire  except  the 
innermost,  which  is  slightly  bifid  The  lobes  vary  from  trifid  to  six-poiuted. 
On  the  left  side  the  first  lateral  saddles  have  the  usual  bifid  form  without 
further  subdivisions.  All  the  saddles  appear  to  have  entire  phylliform  out- 
lines, but  this  may  be  due  to  the  worn  sutures.  The  first  to  fourth  lobes 
are  slightly  digitated,  the  fifth  is  faintly  trifid,  and  beyond  they  are  too 
much  worn  to  show  the  minute  serrations. 

On  the  left  side  the  first  lateral  saddles  have  the  usual  bifid  form,  the 
outer  arm  broad,  pointed  externally,  and  with  only  a  slight  indentation  on 
the  maro-in.  The  second  to  seventh  lateral  saddles  are  entire  and  phylli- 
form; the  eighth  is  broad  and  deepl}-  bifid,  but  is  apparently  only  one 
saddle;  the  ninth  and  tenth  are  entire. 

The  first  to  fourth  lobes  are  faintly  denticulated,  the  fifth  and  sixth 
narrow  and  trifid.  The  seventh  is  totally  unlike  any  other  lobe.  It  seems 
to  be  filed  by  a  pointed  saddle,  the  end  bifid  in  one  case. 

There  is  also  another  specimen  from  the  same  locality,  a  cast  with  a 
part  of  a  living  chamber  preserved.  This  is  about  one-half  of  a  volution 
and  in  tlie  gerontic  stage,  the  last  five  sutures  overlapping.  The  preceding 
sixth  or  eighth,  being  in  the  ephebic  stage,  do  not  overlap.  The  lobes  and 
saddles  are  like  those  of  the  fragment  just  described,  the  sixth  to  the  eighth 
saddle  on  the  right  side  being  bifid  and  the  ninth  entire.  The  saddles  iu 
old  ao-e,  however,  are  flatter  and  the  lobes  become  shorter. 

The  ornaments  are  the  same  as  in  other  specniiens,  but  the  venter 
becomes  broader  in  proportion  to  age;  tubercles  persistent.  The  living 
chamber  is  obviously  nearly  complete  and  must  have  been  at  least  one-half 
of  a  volution  iu  length. 

Three  small  fragments  from  locality  No.  1554,  Seven  Knobs,  near 
Glenrose,  Tex.,  have  tubercles  larger  and  more  prominent,  and  although 
the  sutures  vary  the}  are  near  enough  to  belong  to  the  same  species. 

The  laro-est  specimen  over  one- half  of  a  volution  is  52  mm.  in  diameter. 
Probably,  allowing  for  compression,  this  diameter  is  only  45  nun.     The 


ENGONOCERATID^.  167 

living  chamber  is  about  one-half  of  a  Nolution  and  is  nearly  complete. 
The  venter  broadens  ont,  and  this  specimen  seems  to  be  outgrown,  judging 
from  the  approximation  of  the  last  three  septa.  The  sutures  are  similar  to 
those  of  the  preceding,  but  the  seventh  saddles  are  bifid. 

Specimen  from  locality  1.^45,  Chalk  Mountain,  near  Glenrose,  diameter 
of  ^  olution  50  nmi.,  partly  estimated,  has  seventh  saddle  on  the  right  side 
bifid;  all  others  external  to  this  entire  and  phylliform,  except,  of  course,  first 
lateral.  This  cast  shows  plainly  that  what  is  here  counted  as  the  second 
lateral  is  an  adventitious  .saddle  derived  from  division  of  the  first  lateral 
saddles,  and  the  first  lateral  lobe  is  also  an  adventitious  inflection  arising 
from  a  ]irimitive  marginal  of  the  first  lateral  saddle. 

A  fragment  from  the  Cxoodland  limestone,  Choctaw  Nation,  al>out  lOO 
miles  east  of  Preston,  Tex.,  is  consideral)ly  worn,  but  apparently  of  this 
species.  The  volution  is  33  mm.  fmm  line  of  involution  to  venter  and  is  in 
gerontic  stage,  the  last  six  sutures  overlapping.  The  venter  is  also  rapidly 
broadening,  the  gerontic  tubercles  and  costte  are  larger  than  usual,  and  the 
venter  is  more  asymmetrical  or  zigzag  in  outline.  There  are  nine  saddles 
visible,  and  the  seventh  and  eighth  are  bifid;  the  outlines  of  others  are 
entire.     The  lobes,  owing  probably  to  attrition,  are  all  entire. 

A  specimen  in  the  United  States  National  Museum,  No.  22643,  from 
locality  No.  !)73,  near  Cerrogordo,  Ark.,  has  a  combination  of  characters 
which  appears  to  unite  serpentinum  with  i^ierdenale .  The  sutures  have  the 
broad,  short  saddles  with  flat  bases,  like  those  of  serpentinum  from  near 
Gainesville,  but  the  size  of  specimen,  nodes,  and  aspect  are  similar  to  the 
typical  fossils  of  pierdenale.  The  surface  is  worn  down  somewhat  in  this 
cast,  and  probably  these  resemblances  may.  be  due  to  this  cause.  This  cast 
is  91  mm.  in  whole  diameter;  transverse  diameter  estimated  at  20  mm 

A  cast  in  the  Museum  of  Comparative  Zoology  from  Towash,  Hill 
County,  Tex.,  is  56  mm.  in  diameter;  the  outer  volution  is  27  mm.,  the 
umbdicus  8  mm.,  and  the  opposite  part  of  same  volution  from  line  of 
involution  to  venter  21  mm.  This  is  an  outgrown  specimen,  the  last  six 
sutures  overlapping  those  preceding,  while  in  e])hebic  stage  they  are 
separated  by  a  distinct  interval. 

There  are  the  usual  lines  of  tubercles,  and  the  costse  on  the  outer  jjart  ( if 
the  volution  become  very  decided,  as  in  other  aged  specimens.  The  venter 
is  at  first  narrow,  but  this  becomes  much  broader  at  the  same  time  that  costaj 


168  PSELTDOCERATITES  OF  THE  CRETACEOUS. 

increase  in  .size  in  lust  })Hrt  of  tlie  outer  volution  The  venter  runs  from  2 
to  7  mm.  in  width  on  this  one  volution.  The  living  chamber  is  complete 
hiternallv  and  is  somewhat  less  than  one-half  of  a  volution  in  leno-th.  The 
sutures  resemble  those  of  specimens  described  above  except  that  there  are 
only  seven  saddles,  the  fifth  and  sixth  very  broad  and  bifid,  the  seventh 
entire. 

The  first  to  third  lobes  are  very  slightly  digitated;   the  rest  are  entire. 

Bohm's  studies  of  the  originals  of  tlie  descriptions  of  this  species  have 
been  referred  to  in  the  generic  description.  Whatever  doubts  of  Bohm's  con- 
clusions may  remain  in  the  mind,  it  is  surely  safer  to  follow  such  an  investi- 
gator, who  has  worked  over  the  original  materials,  than  to  indulge  in 
speculations  with  regard  to  the  exact  meaning'  of  von  Buch's  and  Roemer's 
descriptions  and  figures,  about  which  the  most  opposite  opinions  might  be 
reasonably  entertained. 

Engon'ocer.^s  subjectum  n.  sp.  Hyatt. 
PI.  XXI.  tio-s.  2-6;  PI.  XXII,  tigs.  1-.5. 

A  good  cast  of  tins  form  (No.  431  in  Museum  of  Comparative 
Zoology)  is  101  mm.  in  diameter,  the  inner  oldest  part  of  the  outer  voh;tion 
being  partially  destroyed,  so  that  this  could  not  be  measured.  The  living 
cliamber  was  probably,  when  perfect,  not  less  than  one-lialf  of  a  volutiou 
in  length.  The  whole  diameter  was  about  102  nmi.;  the  transverse  diameter 
was  decreased  so  by  compression  that  the  measurement  near  base  of  living 
chamber  could  not  be  relied  on,  but  this  was  18  mm.,  the  ventro-dorsal 
breadth  of  side  being  at  the  same  place  43  mm.  The  living  chamber 
having  been  excavated,  it  was  possible  to  measure  the  interior  volution  in 
the  same  line  with  the  largest  diameter  given  above.  This  was  found  to 
be  73  mm.,  the  largest  volution  being  40  nmi.,  the  umbilicus  7  nnn.,  the 
opposite  part  of  same  volution  26  mm.  No  shell  was  present  on  this  cast. 
The  involution  covers  up  the  entire  side  of  inner  volution  at  diameter  of 
.S6  mm.  This  is  found  in  several  specimens,  but  does  not  apjiear  to  be 
invariable.  There  are  large  nodes  along  the  umbilical  shoulders,  very 
ol)scure  nodose  folds  along  the  central  surfaces  of  lateral  zones,  and 
prominent  elongated  alternating  nodes  along  either  border  of  the  venter. 
These  last  are  finer  in  the  ephebic  stage  than  in  the  gerontic  substages 
At  dianieter   approaching  100  nmi.  the  venter  loses  the  flattened  aspect  ot 


ENGONOCERATID.E.  169 

the  ephebic  stage,  becomes  broader  and  slightl}'  rounded,  but  still  retains 
the  tubercles  and  asymmetrical  aspect  due  to  their  prominence  and  alter- 
nation. The  g-erontic  living  chamber  is  about  one-half  of  a  vohxtion  in 
length  on  tlie  ventral  side,  the  dorsal  side  being  absent. 

The  earliest  suture  in  type  No.  431  at  diameter  of  2(i  nun.  from  line 
of  involution  to  venter  has  eight  saddles  and  seven  lobes  to  the  umbilical 
shoulders.  Beyond  tliis  they  were  not  visible.  The  saddles  are  narrow 
and  phylliform  or  club  shaped;  the  lobes  also  are  clubbed  and  have  primi- 
tive denticulations.  First  lateral  saddle  is  trifid  and  inner  mai-g-inal  lobe  is 
digitated,  the  second  to  fourth  entire,  fifth  to  eightli  l:)ifid.  The  ventral 
lobe  is  longer  than  usual  in  this  o-enus,  but  has  the  usual  form,  divided  bv 
entire  broad  siphonal  saddle.  The  iirst,  second,  and  third  laterals  have 
about  live  denticulations  unequally  divided,  and  the  fourth  is  trifid.  Later 
in  the  gerontic  stage  the  .second  to  fourth  saddles  become  either  bifid  or 
have  more  digitations,  and  the  digitations  of  the  lobes  increase  to  seven; 
the  phylliform  aspect  also  increases. 

When  the  volution  is  about  37  nnn.  in  diameter  from  line  of  involution 
to  venter,  there  are  apparently  about  the  same  number  of  saddles  and 
lobes,  PI.  XXI,  fig.  5.  Tlie  lobes  have  more  denticulations  and  the  third 
saddles  are  also  faintly  bifid.  In  ;mother  specimen,  PI.  XXI,  fig.  6,  same 
locality  at  about  the  same  age,  all  the  saddles  and  lobes  are  shorter  and 
broader  in  proportion,  but  decidedly  phylliform,  the  lobes  are  more  denticu- 
lated, the  first  lateral  saddles  deeply  trifid,  the  second  to  fifth  saddles  entire, 
the  sixth  to  the  eighth  (the  last  one  visible)  distinctly  bifid. 

A  cast  (No.  10755,  Boston  Society  of  Natural  History)  from  Bell  County, 
Tex.,  is  75  mm.  in  whole  diameter.  The  entire  volution  is  39  mm.  from 
venter  to  line  of  involution;  the  umbilicus  is  10  mm.;  the  diameter  oppo- 
.site  from  line  of  involution  to  venter  is  27  mm. 

This  is  in  the  gerontic  stage,  the  last  five  sutures  overlapping.  There 
are  ten  saddles  and  nine  lobes  on  the  left  side.  The  second  to  the  sixth 
are  entire,  the  seventh  to  the  ninth  are  bifid,  and  the  tenth  is  entire.  The 
saddles  and  lobes  have  the  elongated  phylliform  character  of  this  species. 

Locality:  Gabriel,  Williamson  County,  Tex. 

Afje:  Comanche  series,  Wa.shita? 

The  remarkable  and  highly  instructive  specimen  described  below  is  a 
cast  with  an  appro.ximate  diameter  of  55  mm.     It  was  received  from  Dr. 


170  PSF.UDOCERATITES  OF  THE  CRETACEOUS. 

1).  S.  Martin  and  came  from  Grayson,  Tex.  Tlie  sntures  on  the  right  side 
possess  a  decidedh'  unique  aspect,  having-  a  first  lateral  saddle  entirely 
different  from  that  of  any  specimen  of  this  genus  1  have  yet  studied  or  seen 
fio-ured.  The  whole  aspect  of  these  sutures  indicates  a  new  species,  whereas 
the  sutures  on  the  other  side,  although  considerably  abraded,  are  perfect 
enough  in  places  to  show  the  ordinary  form  of  first  lateral  saudle  conunonly 
■found  in  Metengonoceras.  The  sutures  of  the  right  side  are  more  like  those 
oi'  E.  subjectum  than  those  oi  E.  pkrdenah,  but  the}-  are  quite  distinct  from 
l)oth  in  the  aspects  of  the  saddles.  On  the  right  side  there  are  nine  saddles 
and  eiffht  lobes.  The  first  lateral  saddle  is  broad  and  distinctlv  trifid.  The 
inner  arm  is  broad  and  has  the  usual  shape  of  other  species,  being  pointed 
externally  and  running  well  on  to  the  venter.  The  central  arm  is  a  narrow, 
small  marginal  saddle  between  two  small  entire  marginal  lobes;  the  inner 
arm  is  narrower  than  the  outer  arm  and  phylliform.  The  second  to  the 
fourth  saddle  are  entire  and  phylliform,  the  fifth  and  remaining  saddles 
have  flatter  bases.  The  fifth  is  still  entire  and  the  remaining  saddles  also, 
except  the  sixth,  which  is  broad  and  bifid.  This  bifid  character  can  be 
detected  only  on  the  first  part  of  the  outer  volution  where  the  dividing  lobes 
are  not  abraded,  but  even  this  is  open  to  some  doubt. 

The  ventral  lobe  has  the  usual  outline  and  is  symmetrical  in  position; 
nevertheless  the  first  lateral  saddles  on  the  left  side  are  quite  distinct  from 
those  on  the  right  side.  They  have  the  usual  bifid  character  of  specimens 
of  other  species,  and  there  is  nothing  unusual  in  the  outlines  of  the  sutures 
on  this  side.  The  seventh  and  eighth  saddles  are  bifid,  and  the  sixth  is 
entire.  The  ninth  saddle  is  broader  than  on  the  right  side.  The  condition 
of  the  sutures  on  this  side  did  not  admit  of  more  minute  observations.  The 
first  to  the  fourth  lobes  on  the  right  side  were  of  the  usual  form,  but  rather 
coarsely  serrated  and  similar  to  those  of  specimens  from  Bell  County, 
Tex.,  described  above  (collection  of  the  Boston  Society  of  Natural  History, 
No.  l(/755).  It  agreeil  also  with  the  last  in  the  prominence  of  the  middle 
line  of  tubercles. 

Locality:  Grayson,  Tex. 

Similar  sutures  occur  in  a  cast  of  this  .species  kindh"  loaned  me  l^y 
Prof  F.  W.  Cragin,  and  in  this  the  eighth  saddles  are  on  the  umbilical 
shoulders  and  the  broad  ninth  reaches  to  the  line  of  involution:  the  second 
to  the  sixth  saddles  are  entire;   the  seventh  to  the  ninth  are  bilid. 

Locality:  Tarrant  County,  Tex. 


ENGONOCERATID.E.  1  7 1 

The  venter  in  this  species  remains  concave  and  has  a  sharp  ridge  on 
either  side  at  the  ventro-hiteral  angles,  broken  into  waves  by  equally  acute 
but  elongated .  nodes  on  the  casts.  Shells  were  not  present.  In  old  age 
these  nodes  persist,  but  the  ridges  disappear  and  the  venter  becomes  flat- 
tened, and  tinallv  convex. 

A  cast  from  Denison,  Tex ,  Duck  Creek  beds,  United  States  Geolog- 
ical Survey,  has  verv  different  sutures  and  is  also  somewhat  difl^erent  in 
general  aspect.  The  living  chamber  is  complete  in  the  inner  borders  and 
is  considerably  less  than  one-fourth  of  a  volution  in  length.  It  is  in  the 
gerontic  stage;  the  inner  tubercles  are  large,  and  the  outer  ones,  terminating 
short,  fold-like  costa;,  are  also  very  large.  The  venter  is  completely  rounded 
and  mucli  zig'zaga'ed  in  correlation  with  the  larue  tuberculoae  alternating: 
folds  and  nodes  o\'  the  eosta?. 

The  whole  diameter  is  92  mm.;  the  outer  volution,  which  is  somewhat 
reduced  by  gerontic  contraction,  is  42  mm.;  the  umbilicus  is  14  mm.,  tliis 
being  enlarged  in  proportion  to  reduction  of  gerontic  i)art  of  volution,  and 
opposite  from  line  of  involution  to  venter  is  36  mm.  The  saddles  are  quite 
distinct  from  those  of  specimens  described  above,  but  have  the  same  distinctly 
phylliform  aspect ;  the  lobes  are  more  alike  and  with  similar  serrations.  There 
are  nine  saddles  on  the  right  side.  The  first  lateral  has  the  same  deeply 
bifid  form  as  in  specimens  of  this  species.  The  second  to  seventh  have 
rounded  leaf-like  bases;  the  eighth  is  still  phylliform,  but  broadens  out  and 
is  bifid;  the  ninth  is  entire.  The  fir.st  lateral  lobe  is  evidently  very  sligiitly 
divided,  but  the  second  to  the  fifth  are  more  richly  denticulated  than  the 
sixth  and  seventh  and  are  faintly  trifid  ('?);  the  eighth  is  perhaps  entire,  but 
not  plainly  seen.  The  living  chamber  is  shorter  in  this  specimen  than  in 
any  other  example  of  this  species  and  the  nodes  are  more  like  those  of  ser- 
pentimivi,  while  the  sutures  agree  better  with  those  of  subjeetituL 

The  principal  distinction  lietween  this  species  and  its  allies  of  the  same 
genus  lies  in  the  more  elongated  phylliform  saddles  and  lobes. 

Engonoceras  gibbosum  n.  sp.  Hyatt. 

PI.  XXII,  fig.s.  H-10;  PI.  XXIII,  tigs.  1-6. 

The  best  example  of  this  sjjecies  is  an  entire  cast  in  my  collection  from 
Cook  County,  Tex.  This  has  the  median  line  of  nodes  along  the  centnd 
line  of  the  lateral  surface,  the  outer  distinct  and  short  and  no  ])erceptible 


172  PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

costse  between  these.  This  cast,  tlie  type  of  tlie  species,  shows  no  gerontic 
characters  at  the  diameter  of  93.5  mm.  The  greatest  transverse  diameter  is 
at  tlie  nmbihcal  shoulders  and  is  25  mm.,  the  breadth  of  tlie  side  at  the 
same  point  being  50  mm.  The  sutures  are  quite  different  fi-om  those  speci- 
mens described  below,  l)ut  there  is  the  same  general  character:  the  second 
lateral  saddle  and  the  fifth  ai-e  bifid;  the  sixth  is  unequally  trifid;  the  seventh 
is  a  compound  saddle  with  two  bifid  arms;  the  eighth  to  the  tenth  are  entire 
or  flat.  The  more  gibbous  sides,  the  prolonged  stage  during  which  the 
nodes  persist  and  are  sharply  defined,  and  the  large  number  of  bifid  saddles 
characterize  this  species.  The  sutures  are  the  most  complex,  with  exception 
of  Eng.  roeiiieri,  of  any  that  have  been  so  far  descibed  in  the  genus. 

The  largest  fragment  in  the  National  Museum  is  about  three-eighths 
of  a  volution.  Widest  diameter  is  9 1  mm. ;  the  distance  from  line  of  invo- 
lution to  venter  is  50  nnn.  at  the  larger  end  and  38  mm.  at  the  smaller  end; 
and  the  transverse  diameters  are  20  mm.  and  IG  mm.,  respectively.  This 
specimen  was  probably  entirely  uncompressed.  The  venter  is  naiTow  and 
flat  and  the  sides  are  slightly  gibbous  and  highly  convei-gent  outside  of  the 
middle  row  of  obscure  nodes.  Between  these  and  the  umbilical  shoulders, 
however,  a  flattened  zone  is  developed,  which  may  even  slightly  slope 
inward  The  usual  row  of  nodes  is  present  on  the  umbilical  shoulders, 
and  also  the  rows  of  alternating  tubercles  on  each  side  of  the  venter.  The 
latter  are  sharj)  and  well  formed,  elongated,  and  sufficiently  numerous  to 
give  a  decidedly  zig-zag  aspect  to  the  narrow  venter. 

The  venter  is  flat  in  the  early  part  of  the  neanie  stage  and  much 
broader  in  proportion  to  the  volution  than  in  later  stages,  as  it  is  in  most 
species  of  this  genus.  The  volution  has  more  flattened  sides  at  this  age, 
and  the  involution  begins  to  cover  up  the  volutions  to  the  umbilical 
shoulders  even  at  this  early  stage. 

The  sutures  are  well  separated,  as  in  other  shells  of  this  genus,  and 
are  very  remarkable.  There  are  on  the  right  side  ten  lateral  lobes  and 
eleven  saddles  at  the  larger  end  of  this  fragment  and  the  same  number  at 
the  smaller  end.  These  are  more  difficult  to  count  and  quite  different  on 
the  left  side.     The  ventral  lobe  is  synunetrical  and  of  the  typical  form. 

On  the  right  side  the  first  lat<'ral  saddle  is  bifid,  the  outer  arm  short, 
broad,  and  spreading,  the  inner  also  broader  than  in  most  other  forms; 
ihe  outer  is  .subdivided  by  a  minute  marginal  or  slightlv  and  unequally 


ENGONOCERATID.E.  173 

bifid;  the  inner  arm  is  sliglitly  trifid  in  nearly  all  the  sutures,  and  this 
becomes  more  apparent  in  the  older  sutures.  The  lateral  saddles  are 
broadly  phyllitbrm.  The  second  laterals  are  obscurely  and  equally  l:)ifid 
in  all  the  sutures:  the  third  shows  a  faint  tendency  to  become  bifid  only  in 
the  older  sutures;  the  fourth  seems  to  have  a  similar  tendency,  but  this  does 
not  become  demonstrable,  and  it  must  he  described  as  narrower  at  the  base 
and  entire.  The  fifth  is  bifid  in  the  younger  sutures  observed,  and  becomes 
more  distinctly  bifid  with  age;  the  sixth  is  narrower  and  entire;  the  seventh 
is  equally  bifid;  the  eighth  is  also  equally  bifid,  but  the  inner  ai'm  is 
unequally  subdivided  by  a  minute  niarginal;  the  ninth  is  also  equally  bifid, 
and  each  arm  is  also  bifid  with  a  minute  marginal  lobe;  in  some  sutures 
both  are  unequally  divided  and  in  others  the  outer  is  symmetrical,  the  inner 
asA'mmetrical;  the  tenth  is  small  and  entire,  and  the  eleventh  is  very  broad 
and  is  subdivided  by  a  minute  marginal  lobe  introduced  on  this  volution, 
and  the  outer  arm  shows  a  tendency  to  bi'oaden  and  become  bifid  in  the 
older  parts  of  the  same.  The  saddles  are  phylliforin  but  rather  sliort  and 
stumpy  from  second  to  sixth,  then  they  become  very  broad  and  less  phylli- 
form;  the  lobes  have  the  usual  narrow  bases  between  the  expanded  bases  of 
the  saddles  and  spread  out  apicad  between  the  phylliform  saddles.  These 
are  all  apparently  unequally  subdivided,  and  the  digitations  and  serrations 
are  somewhat  more  numerous  in  the  second  to  the  fifth  laterals  than  in  most 
other  species.  The  fir.st  and  sixth  are  simply  trifid,  the  seventh  and  eighth 
bifid,  the  ninth  and  tenth  entire. 

On  the  left  side  the  first  lateral  saddles  have  a  narrower  outer  arm, 
divided  by  a  deeper  marginal  lobe,  and  the  inner  arm  is  not  so  broad  and 
shows  only  a  faint  tendency  to  become  bifid.  The  second  lateral  is  more 
distinctl}-  but  unequally  bifid;  the  third  shows  a  faint  tendency  to  a  trifid 
luidulation;  the  fourth  is  entire;  the  fifth  is  faintly  bifid;  the  sixth  is  dis- 
tinctly but  asynnnetrically  bifid;  the  seventh  is  equally  and  deeply  bifid; 
the  eighth  is  very  liroad  and  also  deeply  bifid,  the  outer  arm  has  the  margin 
faintly  undulated  into  four  nearly  equal  marginal  serrations,  the  inner  arm 
is  asynnnetrically  bifid;  the  ninth  is  also  unsymmetricallv  divided,  the 
outer  jjart  or  arm  is  ver}'  broad,  rather  rounded  basally  and  undulated  into 
three  minute  serrations  on  the  margin,  the  inner  arm  is  a  minute  saddle; 
the  tenth  saddle  is  like  that  of  the  right  side,  but  faintly  bifid  in  the  first 
sutures  seen;  the  eleventh  saddle  is  narrower  than  on  the  right  side  and 


1  74        PSEUD0CERAT1TE6  OF  THE  CRETACEOUS. 

entire.     The  lobes  are  all  shorter,  with  broader  ends  apically  and  with  less 
complex  digitations  than  on  the  right  side. 

One  small  .specimen,  a  cast  from  locality  14!i2,  15  miles  west  of 
Denison,  Tex.,  has  a  diameter  of  46  mm.,  outer  part  of  volution,  23  mm.; 
transverse  diameter,  11  mm.;  umbilicus,  7  mm.;  and  opposite  diameter  from 
line  of  involution  to  venter,  16  mm.;  transverse  diameter,  7.5  mm.  This 
has  the  same  shape  of  venter  and  general  aspect.  The  nodes  of  the  inner 
line  are  present  as  elongated  costje,  which  are  most  prominent  at  the 
umbilical  shoulders  and  much  inclined  orad.  Very  obscure  nodes  could 
be  felt  over  the  more  perfect  surface  of  the  cast  along  the  centran  lateral 
area.  The  cast  was  too  imperfect  along  the  venter  to  observe  nodes,  but 
at  the  beffinuinff  of  this  volution  on  a  small  bit  of  the  shell  of  tlie  venter 
exposed  by  excavation  there  were  smooth  ridges  at  the  ventro-lateral 
angles,  and   the  venter  was  concave. 

The  sutures  in  this  are  crowded  together  luiusually  close  for  shells  of 
this  genus,  the  inner  lobes  and  saddles  overlapping  slightly,  beginning  with 
the  third  lobes  and  fourth  saddl&s.  It  is  probably  a  dwarfed  form  of  tliis 
species,  since  in  the  earlier  part  of  same  vojution  the  sutures  are  well  sepa- 
rated, as  in  other  forms. 

The  ventral  lobes  are  obliterated,  but  sufficient  of  the  first  lateral 
saddles  remain  to  show  that  they  were  unequally  bifid  and  that  the  outer 
arm  was  also  bifid,  the  inner  arm  entire  and  quite  large.  The  second  to 
fourth  saddles  on  the  left  side  were  broad  and  entire,  the  fifth  to  seventh 
symmetricallv  and  deeply  bifid,  the  eightli  very  broad  and  unequally  bifid, 
the  outer  arm  faintly  bifid,  tlie  ninth  alone  entire.  There  is  considerable 
variation  on  the  right  side,  the  sixth  saddle  is  not  deeply  bifid,  the  seventh 
is  unequally  bifid,  the  eighth  is  like  that  of  the  left  side,  but  the  bifidity  of 
the  margin  of  the  outer  arm  is  more  pronounced.  Tlie  ventral  lobe  is 
symmetrical,  but  so  much  worn  down  that  no  observations  were  practicable 
except  at  two  of  the  sutures,  when  it  seemed  to  have  the  usual  generic 
form.  Tlie  living  chamber  was  not  present  in  either  of  the  above- described 
specimens. 

A  small  cast  from  Bell  County,  Tex.,  No.  8301a,  about  a  fourth  of  a 
volution,  is  23  mm.  in  diameter  from  line  of  involution  to  venter,  transverse 
diameter  14  mm.,  two  lines  of  tubercles  and  median  line  of  elevations  well 
defined,   venter  distinctly    concave.      The    sutures  appear    to   have  more 


ENGONOCEKATID.E.  175 

resemblances  to  those  of  the  older  stages  of  this  species  than  to  an}'  others. 
The  ventral  lobe  is  narrow  and  slightly  asymmetrical  to  the  left,  but  the 
first  lateral  saddles  on  both  sides  are  alike.  They  are  both  bifid,  the  outer 
arm  is  entire  but  is  blunter  tiian  usual  on  the  venter.  The  first  to  sixth 
saddles  are  otherwise  like  those  of  the  specimen  described  above;  the  sev- 
enth to  ninth  saddles,  seen  only  on  the  left  side,  are  symmetrically  bifid,  the 
tenth  is  entire.  This  bifidit}'  of  the  internal  saddles  agrees  with  those  of 
uddeni,  but  the  aspect  of  the  volution  and  the  general  form  of  the  saddles 
and  lobes  agree  better  with  those  of  this  species. 

Locality:  Cook  County,  Tex.,  15  miles  southwest  of  Gainesville  and 
15  miles  west  of  Denison. 

Age:  Fredericksburg  division  of  Comanche  series. 

Engonoceras  stolleyi  Bohm. 
PI.  XXIII,  tigs.  7-9;  PI.  XXIV.  tigs.  1-.5. 
Enf/onoceras  stolleyi   Bohm,  1898.  Zeitschr.  Deutsch.  geol.  Gesell.,  Vol.  L,  pi.  5. 

This  species  has  the  flattened  venter,  becoming  alternately  nodose  and 
zigzag  in  old  age,  as  is  characteristic  of  this  genus.  It  is  not  distinguish- 
able from  E.  pierdenale  except  in  the  sutures.  The  lateral  saddles  and  lobes 
are  smaller  than  in  any  other  species  of  this  genus,  and  the  first  lateral 
saddles  are  apt  to  have  the  inner  marginal  saddles  tongue-shaped.  This 
peculiarity  is  noticeable  in  Bohm's  figure  and  in  the  large  fossil  (PI.  XXIV, 
fig.  5). 

Aye:  Fredericksburg  group  [?],  Comanche  series.  Lower  Cretaceous. 

Engonoceras  complicatum  n.  sp.  Hyatt. 

PI.  XXIV,  tigs.  6-8. 

This  is  founded  upon  a  cast  from  near  Austin,  Tex.  The  whole 
diameter,  i)artly  estimated,  is  73  mm.,  the'  outer  volution  is  39  mm.,  the 
umbilicus  9  nun.,  the  volution  opposite  (estimated)  25  mm.  By  the  cast 
alone  this  species  could  not  be  separated  from  Enyonoceras  yihhosum,  but 
the  sutures  are  nevertheless  entirely  different.  A  better  preserved  sjieciinen 
might,  however,  show  some  external  characteristic  distinctions.  There  are 
fourteen  sutures  visible  on  the  outer  volution;  then  comes  a  gap  between 


176        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

them  and  those  on  the  first  quarter  of  the  same  volution.  The  entire 
fourteen  overlap,  but  the  tenth,  eleventh,  and  twelfth  are  nearer  together 
than  any  others.  The  ephel)ic  sutures  on  the  first  quarter  of  this  same 
volution  are  well  separated.  There  are  eleven  slender  saddles  and  ten 
slender  lobes  on  the  left  side.  The  first  lateral  is  narrower  tlian  in  any 
other  species  and  bifid,  with  tongue-shaped  entire  arms;  the  second  and 
third  laterals  are  also  entire  and  linguiform;  the  fourtli  to  the  ninth  are 
l)hylliform  and  bifid;  the  tenth  could  not  be  seen;  the  eleventh  was  entire. 

The  ventral  lobe  is  narrower,  deeper  in  proportion  than  in  other 
species.  There  is  a  smaller  and  contorted  cast  from  Benbrook,  Tex., 
with  similar  sutures  so  far  as  the  bifidity  of  some  of  the  ])rincipal 
saddles  is  concerned.  It  is  very  likely  a  variety  of  this  species.  The 
markings,  so  far  as  can  be  determined,  are  similar.  The  living  chamber  is 
alx)ut  one-half  of  a  volution,  the  last  sutures  overlap,  and  the  shell  was 
evidently  in  the  gerontic  stage.  The  thu-d  latei-al  saddles  were  bifid,  the 
fourth  was  entire,  the  fifth  to  ninth  were  more  or  less  phylliform  and  bifid, 
and  beyond  this  none  were  visible. 

It  differs  from  Protengonoceras  emarginatum  (Cragin)  in  having  pi'O- 
nounced  lines  of  tubercles  along  the  veutro-lateral  angles  and  its  greater 
number  of  lobes  and  saddles,  judging  from  the  descriptions  of  that  species. 
The  characteristics  of  the  venter  and  the  size  as  given  by  him  indicate 
a  larger  species,  with  venter  more  like  that  of  Proten.  gabbi,  A  small 
specimen,  a  cast,  from  15  miles  west  of  Denison,  Tex.,  iias  a  diameter 
of  4G  mm.;  outer  part  of  volution  is  23  mm.;  transverse  diameter, 
1 1  mm.;  umbilicus,  7  nun.,  and  opposite  diameter  from  line  of  involution  to 
venter,  IG  mm.;  transverse  diameter,  7.5  mm.  This  has  same  shape  of 
venter  and  general  aspect.  The  nodes  of  the  inner  line  are  present  as 
elongated  costse,  most  prominent  at  the  umbilical  shoulders  and  much 
inclined  orad.  These  disappear  as  they  pass  the  centran  lateral  surface. 
Nodes  could  not  be  seen  nor  felt  over  the  perfect  surface  of  the  cast,  and 
none  were  visible  at  the  beginning  of  this  volution  on  a  small  bit  of  the 
shell  of  the  venter  exposed  by  excavation. 

The  suture.s  in  this  specimen  are  crowded  together  unusually  close  for 
shells  of  this  genus,  the  inner  loljes  and  saddles  overlapping  slightly, 
be<'-innin«'-   with   the    third   lobes    and   fourth    saddles.     It  is    probably  a 


ENGONOCERATID.li;.  177 

dwarfed  form  of  tins  species,  since  in  the  earlier  parts  of  same  volntion  the 
sntures  are  well  separated,  as  in  other  forms. 

The  ventral  lobes  are  obliterated,  but  sufficient  of  the  lirst  lateral 
saddles  remain  to  show  that  the)'  were  equally  bifid  and  that  the  outer  arm 
was  also  bifid  the  inner  arm  entire  and  quite  large.  The  second  to  fourth 
saddles  were,  on  the  left  side,  liroad  and  entire,  the  fifth  to  seventh 
symmetrically  and  deeply  bifid. 

Locality:  Near  Austin  and  Benbrook,  Tex. 

Age:  Fredericksburg- group,  Comanche  series. 

Engonoceras  emarginatum  (Cragin)." 
Sphetwdisciis e7narginatv«  Cragin,  1893,  Geol.  Surv.  Texas.  Fourth  Ann.  Rept.,  p.  245. 
According  to  Cragin's  description,  this  species  has  the  concave  venter 
until  M  late  stage,  lint  has  the  tubercles  and  sutures  of  this  genus. 

Engonoceras  roemeri  (Cragin). 
Sjyhenodiscnx  roemeri  Cragin,  1893.  Cieol.  Surv.  Texas.   Fourth  Ann.   Rept.,  pi.  -46, 

Cragin  describes  this  shell  as  having  "venter  narrowly  truncate,  the 
ventro-lateral  angle  at  first  sharp,  becoming  on  the  body-chamber  subtu- 
berculate-siuuous."  This  and  the  general  outlines  of  the  sutures,  if  they  are 
supposed  to  be  deprived  of  their  marginal  saddles,  as  they  must  have  been 
in  the  young  of  this  shell  before  these  were  developed,  has  caused  me  to 
refer  the  species  provisionally  to  this  genus  The  sutures  are,  however, 
obviously  more  complex  as  figured  by  Cragin  than  in  any  other  known 
form  of  Enfionoceras.  The  principal  saddles  are  all  bifid,  trifid,  or  ([uadrifid, 
and  the  smaller  saddles  inside  of  Avliat  appears  to  be  the  fourth  saddles  are 
mostly  bifid. 

Mr.  Stanton  has  writteli  as  follows  regarding  this  form: 

According  to  Cragin,  this  is  from  the  "alternating  bed.s" — that  is,  the  Trinity 
division — not  Fredericksburg,  as  given  in  your  MS.  If  this  be  true  (and  Mr.  Taff's 
stratigraphic  data  look  all  right),  the  form  is  pro))ably  the  oldest  one  of  thi.s  group 
that  we  have  from  the  Comanche  series. 

Locality:   Iredell,  Bosque  County,  Tex. 
Age:  Comanche  series,  Glenrose  beds. 


"  See  p.  157,  where  this  species  is  doubtfully  referred  to  Protengonoceras. — T.  W.  S. 
MON    XLIV — 03 12 


1 78  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

NEOLOBITES  Fischer. 

The  sutures  of  this  geuus  have,  perliaps,  simpler  outhiies  than  those 
of  anv  other  Cretaceous  ammonoid,  and  have  been  supposed  to  phice  the 
genus  somewhere  near  Tissotia.  They,  however,  differ  decisively  fmm 
those  of  an}'  of  this  "roup  in  having-  long  phylliforin  saddles  and  a  very 
peculiar  ventral  lobe.  The  form,  ornamentation,  and  old  age  of  the  species 
from  Tunisia,  described  by  Peron,  would  place  it  in  the  genus  Placcnticeras, 
if  no  sutures  were  visible.  But  the  sutures  and  ornamentation  agree  with 
those  of  Engonoceras,  and  sho\\'  that  it  is  probably  a  member  of  the  same 
family.  Choffat's  researches  have  placed  this  conclusion  on  a  secure  footing. 
His  Neolohites  inbrayeanus  may  not  be  identical  with  d'(  )rbign}''s  species, 
l)ut  it  is  surely  a  close  ally,  and  he  gives  the  sutures  in  full,  and  these 
show  the  \entral  lobes  and  siphonal  saddles  and  first  laterals  to  be  similar 
to_those  of  Engonoceras.  If  the  young,  when  seen,  prove  to  have  a  similar 
development,  the  evidence  will  be  complete. 

Neolobites  vibrayeanus  (d'Orbigny). 

Ainmonitcs  vihrayeanii><  d'Orbigny,  1840,  Terr.  Cret.,  pi.  90,  iigs.  1-3. 
J^.olohites  vthrayenuits  Choffat,  1898,  Faune  Cret.  du  Portugal,  Vol.  I,  2d  series,  pi. 
5,  figs.  2,  .5  (not  Iigs.  3,4.) 

This  species  as  figured  by  d'Orbigny  has  led  to  great  confusion,  owing 
perhaps  to  the  absence  of  a  sufficient  representation  of  the  details.  Choffat 
has  figured  a  species  from  Portugal  which,  if  not  identical,  is  })robably 
similar  to  d'Orbigny's  species.  All  the  characters  coincide  with  the  posi- 
tion here  given  to  this  form.  A  number  of  species  are  confused  under  this 
name,  but  the  data  given  are  not  sufficient  to  separate  them. 

Locality:  France  and  Portugal. 

Age:  Cenomanian. 

Neolobites  choffati  n.  sj).  Hyatt. 

PL  XXV,  Iigs.  1-t. 

Weoldbitef  I'ihntij.'dnns  Choffat,   1898,  Faune  Cret.  du   Portugal,  Vol.    I,  :.'d  series, 
1)1.  .5,  figs.  3,4  (not  figs.  2,  5.) 

This  is  obviously  distinct  from  inbrayeanus,  as  is  shown  by  the  broad 
venter  and  distinct  sutures  as  well  as  the  more  gibbous  form. 
Locality:   Portugal. 
Age:  Cenomanian. 


ENGONOCERATID.E.  179 

Neolobites  peroni  n.  sp.  Hyatt. 

Neolobites  vlhrnt/eauH-y  Peron.  1S!)0.  ^loll.  Cret.  de  la  Tuiiisie,  pi.  IM.  tigs.  1.  3. 

A  highly  compvesscd  shell  with  navrow  flat  venter  bordered  on  either 
side  by  a  line  of  small,  closely  set  tubercles  with  luimerous  costse  on  the 
flat  sides,  focussed  into  a  very  few  large  nodes  near  the  umbihcal  shoulder. 
The  involution  is  almost  if  not  quite  complete.  Tlie  umbilicus  is  not 
flgured  in  Peron's  flgure,  but  it  must  have  lieen  very  small.  In  extreme 
aare  these  nodes  recede  farther  from  their  flrst  iiosition,  the  ventro-lateral 
lines  of  small  tubercles  disappear  and  the  venter  becomes  elevated  and  is 
represented  in  the  last  stage  as  subacute.  There  are  five  or  six  lateral  saddles 
in  this  species,  according  to  Peron's  drawing.  Peron  considered  this 
form  to  be  distinct,  but  did  not  describe  it  as  a  new  species. 

Locality:  North  Africa. 

Age:  Cenomanian. 

METENGONOCERAS  n.  gen.  Hyatt. 

The  shell  is  compressed  as  in  Emionoceras  and  the  involution  covers 
the  greater  part  of  the  sides  of  the  internal  volutions.  Broad,  fold-like 
sigmoidal  cost;*  are  present  in  some  species  and  faint  tubercles  have  been 
observed  in  rare  cases  on  casts.  No  well-preserved  shells  have  been  so  far 
seen  nor  described  The  venter  in  the  neanic  stage  is  comparatively  broad 
and  slightly  concave;  in  the  ephebic  stage  it  becomes  very  narrow,  but 
retains  a  linear  concavity;  in  the  full  ephebic  stage  it  becomes  acute,  and 
in  o-erontic  stag-e  subacute  and  then  rounded.  The  sutures  do  not  differ 
materially  from  those  of  Emjonoccras ;  the  distinction,  so  far  as  known,  lies 
in  the  development  of  the  venter  and  absence  of  nodes.  The  young  were 
similar  to  the  adults  of  Frotengonoceras,  as  are  those  of  other  genera.  The 
principal  or  outer  lateral  lobes  and  saddles  are  short,  the  lobes  narrow  and 
entire  between  the  entire  and  more  or  less  rounded,  often  phylliform  l)ases 
of  the  principal  saddles.  The  apical  ends  of  the  lobes  are  denticulated,  but 
the  marginals  are  entire,  pointed,  and  the  saddles  blunter  but  also  entire. 
The  smaller  inside  of  the  jjrincipal  outer  saddles  are  often  bifid.  The 
ventral  lobe  is  narrow  orally,  very  short  and  broad  a|)ically,  with  two 
entire  arms,  and  is  divided  by  a  depi'essed  but  more  or  less  subacute  entire 
siphonal  saddle.     The  first  lateral  saddles  in  most  species  are  broad  and 


180        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

bifid,  the  outer  arms  more  or  less  acute  at  the  outer  aug'les  of  the  bases,  and 
the  inner  arm  narrower  and  tong-ue- like.  One  of  the  marked  characters 
of  this  g-enus  is  the  absence  of  differentiation  between  the  parts  of 
the  suture  at  later  stages  of  growth.  The  princi{)al  lateral  saddles  and 
lobes  can  not  in  many  specimens  be  distinguished  from  the  so-called 
auxiliary  laterals,  and  I  have  not  attempted  to  do  this  in  my  descriptions. 
In  some  specimens,  on  the  other  hand,  especially  young  ones,  there  seem 
to  be  plainl}^  only  three  principal  lateral  saddles  or  lolies,  but  in  others 
there  seem  to  l)e  four  or  even  five.  The  metaneanic  substage  in  one 
species  showed  the  primary  division  of  the  primitive  first  lateral  saddle  into 
three,  and  in  several  specimens  in  a  late  neanic  substage  it  seemed  obvious 
that  this  subdivision  was  maintained  and  that  the  first  lateral  of  the 
derivative  or  principal  series  became  bifid  late  in  the  life  of  the  shell.  First 
lateral  saddles  are  therefore  morphologically  double,  even  when  they  are 
so  fully  divided  that  the}'  have  to  be  considered  as  two  saddles,  as 
in  Metenyonoceras  dumhli.  In  most  species  there  is  no  difficulty  in  seeing 
this,  but  in  about  all  of  them  the  line  between  the  three  principal  laterals 
and  the  auxiliaries  can  not  be  drawn,  nor  between  the  principal  lobes  and 
the  auxiliaries.  Here,  however,  as  in  Engonoceras,  there  are  but  three 
principal  laterals,  if  the  first  lateral  is  properly  defined  as  double  or  bifid. 

The  subacute  venters  of  the  species  in  this  genus  have  lead  to  confusion 
with  Sphenodiscus  and  its  allies.  The  ontogeny  of  the  latter  separates  the  two 
generically,  but  the  latter  might  be  considered  an  accelerated  form  of  the 
same  family,  as  stated  above  in  the  description  of  the  famih-,  but  for  the 
sutural  characters  which  show  that  Sphenodiscus  belongs  in  the  Placenticeran 
stock. 

Metengonoceras  inscriptum  n.  sp.  Hyatt. 

PI.  XXV,  tigs.  o-;t:  PI.  XXVI,  Hgs.  1-4. 

One  entire  cast  is  80  mm.  in  diameter.  The  diameter  from  line  of 
involution  to  venter  is  42  nun.  at  largest  part,  the  transverse  being  Hi  mm. 
Both  measurements  are  a  trifle  short  of  what  they  would  be  in  a  more 
pei-fect  cast.  Opposite  this  the  same  diameter  is  29  mm.  without  shell, 
the  umbilicus  being  9  mm. 

A  fragment  somewhat  vounger  from  same  locality  was  not  compressed 
so  as  to  destroy  the  shape.  This  had  the  same  form,  but  was  not  so  con- 
cave near  the  iimbilicus  and  had  no  folds.     The  volutions  were  flat  on  the 


ENGONOCERATID.E.  181 

venter  in  the  n^anie  stage,  and  were  ()l)vi()usly  siinilar  to  Protengonoceras  in 
their  young.  The  smaller  Iragmeut,  nearly  one-half  of  a  volution,  with 
center  partly  preserved,  is  52  mm.  in  diameter,  and  the  venter  is  worn,  Ijut 
in  places  where  sutures  are  perfect  the  venter  is  narrowly  rounded.  In  the 
largest  cast,  at  about  the  same  age,  I  was  able  to  demonstrate  hv  excava- 
tion thnt  the  shell,  although  very  narrow,  was  thick  and  distinct!}'  concave 
on  the  venter.  There  were  apparently  no  large  tubercles  at  an}-  stage. 
The  first  lateral  .saddles  in  the  small  fragment,  at  a  diameter  of  over  52  mm., 
were  broad,  very  short,  and  had  the  inner  angle  furnished  with  a  large 
marginal  lobe  and  saddle. 

The  second  to  fifth  saddles  on  tlie  right  side,  and  the  second  to  sixth 
on  the  left  side,  are  entire,  the  sixth  on  the  right  and  seventh  on  the  left 
being  the  first  of  the  bifid  saddles.  The  other  saddles  are  all  bifid,  except, 
perhaps,  the  innermost  pair,  but  this  was  not  seen. 

The  lobes  are  too  much  worn  down  to  show  their  minute  d'Vitations 
except  in  a  general  way.  The  ventral  lobe  and  minute  median  saddle  are 
present  and  the  first  lateral  saddles  are  narrow.  On  the  youngest  and 
least-worn  part  of  the  larger  specimen  on  the  right  side,  the  first  lateral 
saddles  show  .slight  marginal  lobes  and  saddles  at  each  of  the  inner  angles, 
but  there  are  minute  marginal  lobes  on  the  outer  parts  of  these  saddles. 
Several  of  them  show  this  division,  and  one  is  distinctly  trifid.  On  the 
older  jjarts  of  the  same  specimen  tliey  are,  however,  distinctly  entire  as  in 
the  other  fragment,  and  this  I  think  is  the  normal  character.  The  wearing 
to  whicli  it  had  been  exposed  caused  me  at  first  to  count  three  entire 
saddles  on  the  left  side  and  four  on  the  older  jjarts  of  the  same  volution. 
It  is  obvious,  however,  that  it  is  the  sixtli  saddles  that  are  bifid  on  both 
sides.  The  remaining  saddles  are  bifid  to  the  line  of  involution.  In  both 
of  these  specimens  there  are  ten  saddles  and  nine  lobes,  but  there  was 
probably  in  each  a  lobe  on  the  line  of  involution.  The  youngest  sutures 
were  about  5  mm.  distant,  but  the  last  nine  lost  distance  rapidly  and  were 
more  or  less  irregular,  and  in  the  last  four  the  second  lateral  saddles 
overlapped  slightly  the  second  lateral  lobes. 

The  larger  cast  has  three  nnich-worn  fragments  of  the  attached  valves 
of  an  ostrean  on  the  right  side,  which  had  evidently  been  exposed  above 
the  calcareous  nmd  while  in  the  same  condition  as  at  present,  namely,  a 
distorted  fossil  cast,  and  the  ostreans  grew  upon  the  surface  of  the  cast 
Itself.     That  the  cast  had  already  suff'ered  from  attrition  and  compression 


182  PSEUDOCERATITES  OF  THE  CRETACEOrS. 

was  shown  l)y  the  nccurate  fittmg  of  the  ostreaii  shells  into  tlie  irregularities 
of  the  broken  and  worn  surface.  A  few  other  lower  valves  were  removed 
to  study  the  sutures,  l)ut  in  no  case  could  1  find  an}'  remnants  of  the  shell 
of  Enffonoceras  between  the  bases  of  attachment  of  the  lower  valves  of  the 
ostrean  and  the  surface  of  the  cast.  The  specimens  still  left  u])on  the  cast 
show  these  facts  also.     The  smaller  specimen  was  nuich  smoother  and  clean. 

A  much-distorted  fragment  from  another  locality,  9  miles  from  Austin 
on  Beecaves  road,  of  what  seemed  to  be  the  gerontic  stage  of  this  species 
is  85  mm.  from  line  of  involution  to  venter  and  this  is  verv  near  to  the 
actual  diameter  in  a  perfect  cast.  The  gi-eatest  transverse  diameter  is  35 
mm.  and  is  somewhat  greater  than  in  a  perfect  cast  of  the  same  age.  This 
s])ecimen,  however,  has  the  sutures  well  shown  on  the  right  side,  and  the 
differences,  with  one  exception  given  below,  when  compared  with  the  first 
specimen  described,  t-an  be  accounted  for  as  probably  due  to  greater  age. 
The  saddles  and  lobes  are  all  much  nearer  together,  the  overlapping  begin- 
ning between  the  third  saddle  and  second  lobe.  The  curvature  was  the 
same  as  in  the  smaller  specimen. 

The  tenth  saddle  is  the  first  liifid  one  and  the  remainder  are  bifid  and 
near  the  umbilicus  become  very  broad. 

This  difference  cai\  not  be  accounted  for  by  supposing  that  the  seventh 
and  eighth  saddles  have  become  completely  divided  liy  the  advance  in 
development  of  the  marginal  lobes,  thus  adding  two  saddles  to  the  series, 
but  indicates  some  oi-iginal  variation  in  this  shell. 

The  ventral  lobe  could  not  be  defined  and  the  condition  of  the  other 
lobes  only  enabled  an  observer  to  see  that  they  were  digitated  and  near  the 
umbilicus  they  were  too  much  worn  to  say  even  this  much.  The  lengtli- 
enino-  out  of  the  saddles  by  growth  does  not  decrease  the  phylliform  aspect 
of  the  bases  and  the  lobes  l^ecome  nan-ower  and  longer  without  apparently 
altering  much  in  general  outline. 

Locality:  Twelve  miles  northeast  of  Decatur,  Tex. 

Age:  Fredericksburg  group,  Comanche  series.  Lower  Cretaceous. 

Metengonoceras  inscriptum  var.  ? 

This  is  a  fragment  of  a  volution  of  a  large  specimen,  showing  only  a 
part  of  one  side.  It  is,  however,  interesting,  for  the  characteristics  of  the 
lobes  and  saddles  given  on  PI.  XXV,  fig.  8,  show  variations  in  the  forms  of 
these.     A  specimen  from  west  of  Walnut  Springs,  Tex.,  kindly  loaned  me 


.       ENGONOCERATID.E.  183 

by  Professor  Cragin,  shows  the  subacute  venter.  The  eighth  saddles  are 
bifid  in  this  fragment  nnd  there  are  only  ten  on  the  riglit  side,  witli  large 
unequally  bifid  first  laterals  as  in  large  fragment  described  above. 

Locality:  Fifteen  miles  west  of  Denison,  Tex.  Locahty  1492,  U.  S. 
Geological  Survey. 

Age :  Fredericksburg  group  of  Comanche  series. 

One  fragment  is  55  mm.  from  line  of  involution  to  venter  without  the 
shell.  The  first  lateral  saddle  is  deeply  bifid,  and,  counting  this  as  one, 
there  are  only  five  entire  saddles,  some  of  which,  probably  owing  to  wear, 
appear  to  show  a  faint  tendency  to  become  bifid.  The  sixth  to  the  ninth 
saddles  are  distinctly  bifid;  the  tenth  is  a  very  broad  saddle  with  three 
minute  marginal  lobes,  and  the  eleventh  is  another  liroad  saddle  which  is 
entire  to  the  line  of  involution.  On  the  opposite  or  right  side  the  broad 
tenth  saddle  is  divided  into  two  bifid  saddles,  so  that  there  are  obviously 

twelve  on  that  side. 

LocaUUj:  Cow  Greek,  Travis  County,  Tex.     N...  19105,  U.  S.  National 

Museum. 

Metengonockras  ambiguum  n.  sp.  Hyatt. 

PI.  XXVI.  tigs.  5-7. 

One  nearly  entire  cast  of  this  form  is  79    nnn.  in  diameter,  the  last 

volution  44  mm.  from  line  of  involution  to  venter,  the  undjilicus  6  mm.,  and 

the  opposite   part  of  volution  29  nnn.     The  greatest  transverse  diameter 

through  median  surface  is  17  nnn.  and  is  somewhat  less  than  in  a  perfect 

specimen. 

The  sutures  have  smaller  saddles  than  at  the  same  age  in  M.  inscriptum, 
are  also  less  distant  throughout,  become  still  more  approximate  in  later 
stages,  and  are  straighter.  There  are  thirty  septa  in  tliis  specimen  to  twenty- 
four  in  inscriptum  at  same  diameter.     The  sixth  saddles  were  bifid  on  both 

sides. 

Fold-like  costse  along  the  inner  part  of  the  volution  are  plainly  visible 
and  there  are  small  nodes  along  the  ventro-lateral  angles,  the  venter  being 
here  famtly  sinuous.  The  venter  was  much  eroded,  but  in  two  places  it 
showed  a  narrowly  rounded  area  and  on  the  end  of  this  volution  is  subacute. 
pJxcavation  was  not  very  successful  and  I  could  only  demonstrate  that  the 
venter  was  extremely  narrow  in  the  ephebic  stage  and  perhaps  not  distinct 
from  that  of  Enr/.  inscriptum  at  the  same  age. 


184  PSEI'DOC'ERATITES  OF  THE  CRETACEOUS. 

This  cast  was  considerably  worn.  The  right  side  was  free  of  encrusting 
ostreans;  on  the  opposite  (left)  side  there  were  a  few,  some  of  which  were 
removed.  No  shell  was  found  between  these  and  the  cast.  They  had 
evidently  grown  upon  this  cast  and  not  upon  a  living  or  dead  sliell.  Tliis 
can  also  be  seen  by  studying  the  remaining  shells,  one  complete  lower  valve 
and  part  of  another. 

Locality :  Nine  miles  from  Austin,  Tex.,  on  the  Beecaves  road. 

Age:  Comanche  Peak  limestone,  Fredericksburg  group  of  Comanche 
series,  Lower  Cretaceous. 

Metengonoceras  acutum  n.  sp.  Hyatt. 
PI.  XXVI,  lig.  8;  PI.  XXVII,  figs.  1,  2. 

The  type  specimen  of  this  species  in  Boll  collection  in  the  Museum 
of  Comparative  Zoology  is  a  fragment,  bur  this  shows  the  whole  diameter 
to  have  been  approximately  100  mm.  Tlie  outer  volution  from  line  of 
involution  to  venter  is  54  mm ,  the  umbilicus  5  nun.,  and  the  same  volution 
opposite  nmst  have  been  about  40  to  41  mm. 

The  form  is  much  compressed  and  involute,  with  more  acute  venter 
than  in  M.  inscriptum.  The  umbilical  shoulders  also  in  this  species  are 
more  prominent  and  entire,  and  short  but  distinct,  broad,  fold-like  costse 
are  present  near  the  umbilical  shoulders,  but  do  not  cross  them.  There 
are  no  tubercles  on  the  fragments  observed. 

The  marginal  lobes  of  the  first  lateral  saddles  on  both  sides  are  narrow 
and  divided  bv  a  minute  marginal  saddle  or  bifid.  The  first  laterals  are 
unsvnmietrically  trifid,  the  second  to  the  fourth  are  symmetrical  and  quad- 
rifid,  the  fifth  is  of  the  same  type  but  not  regularly  divided.  All  of  these 
are  very  narrow  at  the  bases  between  the  expanded  bases  of  the  saddles  and 
spread  out  apicad  into  the  marginal  divisions.  The  sixth  lobe  is  narrow 
and  bifid,  with  a  small  marginal  saddle,  and  the  seventh  similai-,  but  witli  a 
lar<>er  tongue-like  marginal  saddle,  and  the  minor  lobes  on  either  side  of 
this  are  also  subdivided  or  bifid.  The  eighth  and  ninth  are  distinctly  l)Ut 
very  faintly  trifid,  and  nuich  longer  than  the  narrow  marginal  lobes 
described  above  as  dividing  the  broad  saddles  of  this  part,  which  are  faintly 
bifid.     The  tenth  lobe  was  visible  but  not  distinct  enough  for  description. 

Both  specimens  were  too  much  crushed  in  the  central  parts  to  give 
any  accurate  data  for  the  description  of  the  younger  stages.     Nevertheless 


ENGONOCERATID.E.  185 

there  are  strong  indications  that  the  venter  became  acnte  in  an  early 
ephebic  substage. 

The  matrix  of  these  s))ecimens  is  a  red,  apparently  calcareous,  clay 
stone,  and  indicates  a  distinct  formation  from  that  containing  the  species  of 
Place nticer as  cited  from  the  same  locality  and  also  in  the  Boll  collection  in 
the  Museum  of  Comparative  Zoology.  They  have  remnants  of  the 
nacreous  layer  and  one  has  the  shell  still  left  in  the  umbilicus.  The 
interior  is  so  much  crushed  together  that  it  is  impossible  to  say  that  the 
venter  was  or  was  not  concave  in  the  internal  volutions.  Certainly,  so  far 
as  the  cast  goes,  the  outer  volution  was  iniquestionably  subacute. 

Three  fragments  in  Cragln's  collection  from  the  Grayson  marl,  one- 
half  to  three-fourths  mile  southeast  of  the  Union  Station,  at  Denison,  Tex., 
have  the  phylloidal  saddles  and  long  complex  lobes  of  this  species  and  aLso 
subacute  venters.  The  last  volution  of  one  of  these  fragments  reaches 
ventro-dorsal  diameter  of  60  mm.  while  still  septate,  and  has  a  transverse 
diameter  of  24  mm.  The  sutures,  however,  are  too  much  aliraded  for 
efficient  observation. 

The  peculiar  first  lateral  saddles  of  this  species,  the  extremely  phylli- 
form  saddles,  narrow  lobes  with  spreading  and  digitate  extremities,  and 
straightened  sutures,  separate  this  from  M.  inscriptiim.  The  larger  size  of 
the  lobes  and  saddles  enables  one,  as  Avell  as  the  more  persistent  acuteness 
of  the  venter  in  the  gerontic  stage,  to  distinguish  it  from  M.  dumhli. 

Mr.   Stanton  has  written  as  follows  with  reference  to  this  fossil:    "I 

think  this  is  certainly  from  the  Upper  Cretaceous  and  probably  from  the 

Eagle  Ford  shales,  like  the  other  specimens  with  the  same  locality  label. 

Such  brownish-red  concretions  are  common  in  weathered  portions  of  the 

Eagle  Ford  shales." 

Local itij:  Elm  Fork  and  West  Fork  (Horton's  mill),  Dallas  Countv, 
Tex. 

Aye:   Probably  Eagle  Ford  shales,  Colorado  group,  Upper  Cretaceous. 
Metengonocekas  DUMBLi  (Cragin.) 

PI.  XXVIl,  tigs.  3-14. 

Sphenodiscv.s  dumhli  Cragin  (pai-s),  189.3,  Geol.   Surv.  Texas,  Fourth  Ann.   Rept., 
p.  2-t3,  pi.  U. 

A  superb  specimen  in  collection  United  States  Geological  Survey, 
diameter  94  nun.,  although  in  three  pieces  and  with  nepionic  stage  and  part 


186        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

of  outer  volution  absL-nt,  is  otherwise  perfect  and  shows  many  essential  facts 
with  reo-ard  to  the  affinities  of  this  o^enus.  The  last  half  of  outer  volution 
or  oreater  part  of  living  chamber  is  in  the  gerontic  stage.  Tliis  sliows  tliat 
the  living  chamber  was  at  least  one  half  of  a  volution  in  length.  Cragin,  who 
had  this  cast  in  hand  as  part  of  his  materials,  describes  his  specimens  as  being 
"verj-  sharp  in  the  young  [my  adult],  becoming  obtuse  along  the  liody- 
chamber  of  adult  [my  old  age]  specimens."  The  well  preserved  part  of 
the  o-erontic  venter  in  this  cast  is  23  mm.  long  and  for  a  few  millimeters  is 
rounded,  with  two  almost  imperceptible  ridges  on  the  ventro-lateral  angles, 
then  a  hollow  occurs  as  if  the  shell  had  been  injured,  and  this  is  continued 
to  the  end  of  the  fragment  by  a  very  faint  channel  bordered  by  faint  ridges. 

The  young  in  the  nepionic  stage  has  the  usual  rounded  volution:  tlie 
paraneanic  substage  was  compressed  with  Hat  sides,  deep  involution,  and 
broad  concave  venter,  with  entire,  acute  ridges  on  the  borders.  This  stage 
is,  in  other  words,  like  the  ephebic  stage  of  Protengonoceras,  as  has  been 
already  stated  from  examination  of  less  perfect  specimens.  This  substage 
was  introduced  gradually  by  the  intervention  of  a  metaneanic  substage 
having  a  helmet-shaped  section  with  a  flattened  venter  and  an  ananeanic 
substage  with  transitional  characters  between  this  and  the  nepionic  rounded 
volution,  but  not  having  the  flattened  zone  on  the  venter.  In  the  anephebic 
substage  the  compression  and  flattening  continues  to  increase,  tla-  involution 
remains  constant,  and  a  very  narrow  channel  .still  persists  on  the  venter. 

In  the  full  ephebic  condition  this  disappears  and  the  venter  becomes 
acute.  In  the  paraephebic  substage  the  venter  is  subacute,  the  sides  a 
trifle  more  convex,  and  volution  somewhat  broader  in  proportion  to  the 
ventro-dorsal  diameters,  but  these  changes  are  slow  until  in  extreme  age, 
the  paragerontic  substage,  when,  as  stated  above,  the  venter  becomes 
rounded.  I  have  frequently  alluded  to  the  reinstatement  Ijy  degeneration 
at  the  end  of  a  cycle  or  in  the  adult  of  characters  analogous  to  those  of , 
younger  stages,  lu  tliis  specimen  the  rounded  venter  of  the  paragerontic 
substage  has  a  faint  concavity,  and  this,  after  what  seems  to  have  been 
some  injury  to  the  edge  of  the  venter,  becomes  converted,  as  described 
above,  into  a  faint  channel  with  ridges  on  the  outer  borders.  There  are  no 
marks  of  tubercles,  nor  costse,  nor  folds  at  any  stage  so  far  as  these  could 
be  seen. 


ENGONOCERATID^.  187 

The  sutures  have  short  broad  saddles  with  narrow  lobes,  digitated 
only  at  the  apical  ends,  and  while  the  saddles  remain  about  the  same,  the 
lobes  increase  somewhat  in  the  number  of  their  digitations  and  in  length 
with  age.  They  are  (juite  different  on  the  right  and  left  sides.  The 
siphuucle  is  eccentric  to  the  right,  and  ventral  lobe  follows  this  organ,  but 
there  is  no  verv  marked  difference  between  the  first  lateral  saddles  in 
consequence  of  this. 

Oh  the  right  si'le  the  first  lateral  has  two  liranches  so  deeply  divided 
bv  a  bifid  marginal  lobe  tliat  it  is  really  split  into  two  distinct  entire 
saddles,  but  these  are  more  widel}'  separated  than  in  MeteiKj.  acntitm,  and 
are  more  nearly  equal  in  size  and  aspect.  Counting  these  as  two  saddles, 
there  are  thirteen  saddles — ten  narrf)w,  entire,  and  phylliform,  and  three 
broad  and  bifid,  the  eleventh  very  deeply  bifid,  and  the  twelfth  and 
thirteenth  successively  less  deeply  divided.  The  first  and  second  lobes 
are  bifid,  tlie  third  to  sixth  l)ifid,  but  with  four  to  eight  digitations;  the 
seventh  to  tenth  simplv  bifid;  the  eleventh  and  twelfth,  especially  the 
eleventh,  are  divided  by  longer  tongue-shaped  saddles. 

On  the  left  side  the  differences  are  as  follows:  The  ninth  to  eleventh 
saddles  are  broad  and  bifid,  the  twelfth  is  broad  and  entire,  the  thirteenth 
is  very  broad  and  has  a  sinuous  base,  and  inside  of  this  a  very  minute  lobe 
shows  that  there  is  a  small  fourteenth  saddle.  The  eighth  to  the  tenth 
lobes  are  simply  bifid,  the  eleventli  is  unequally  l^ifid,  but  has  no  long 
tongue-shaped  marginal  saddle;  the  twelfth  is  entire,  and  there  is  an 
excessively  minute  marginal  thirteenth,  as  stated  above. 

In  the  adult  staere  from  the  fifth  saddles  inward  on  both  sides  the  sutures 
overlap  slightly  and  the  outlines  are  easily  separable,  but  in  the  last  five 
sutures  this  overlapping  spreads  to  the  third  saddles  and  lobes  and  the  out- 
lines are  more  compressed.  This  is  accompanied  by  a  shortening  up  of 
the  saddles  and  lobes  and  a  corresponding  return  t)f  the  younger  proportions 
and  aspect. 

In  the  metaneanic  substage  the  primitive  first  lateral  is  divided  into 
three  low  broad  saddles  l)y  simple  indented  marginal  lobes,  and  the  magno- 
sellarian  saddles  are  also  divided,  lint  the  number  of  these  was  not  ascer- 
tained.    There  were,  however,  only  a  few  of  these. 

Locality:  Four  miles  east  of  Whitesboro,  Tex. 

Age:  Eagle  Ford  shales,  Colorado  group,  Upper  Cretaceous. 


188        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

PLACENTICERATID^  Hyatt. 

The  vouiig  are  .similar  to  the  aduhs  of  Phigouoceratida^,  having  con- 
cave A'^enters  bordered  usually  by  contimious  ridge.s  with  compressed  volu- 
tiftns,  the  lateral  zones  converging  outwardly.  In  later  stages  of  genera 
the  venters  are  either  concave,  flat,  or  rounded,  but  there  is  no  true  keel 
present,  although  the  venter  may  become  acute  in  some  species  at  a  late 
stage  of  growth.  The  volutions  in  the  earlier  stages  subsequent  to  the 
nepionic  are  apt  to  be  more  or  less  compi-essed,  the  venters  assuming  early 
the  characters  described  above,  any  further  sharpening  of  the  venter  occur- 
ring in  later  stages.  The  principal  lateral  saddles  are,  so  far  as  known,  bifid 
in  the  A^oung  and  show  in  most  groujis  a  tendency  to  become  more  or  less 
tritid  in  later  stages.  The  multiplication  of  inflections  of  the  suture  lines 
increases  with  the  involution  of  the  whorls  by  growth  and  they  become 
very  numerous  in  some  genera. 

PLACENTICERAS  Meek. 

The  species  of  this  genus  could  be  readily  distinguished  if  it  were  not 
for  the  great  range  of  form  in  the  gerontic  stage,  which  occurs  in  dwarfed 
as  well  as  in  large  sjjecimens,  and  is  continually  mistaken  for  the  ephebic 
stage. 

The  neanic  shell  is  smooth,  compressed,  with  at  first  a  flat  and  then  a 
concave  venter  bordered  by  smooth,  entire  ridges  on  the  shell  ;ind  on  the 
casts,  l)ut  has  a  stouter  volution  than  later  stages.  It  is,  in  other  words,  like 
the  ephebic  stage  of  Protem/o)ioreras  in  external  characters,  lint  the  sutures 
are  of  the  Placenticeran  type.  Subsequently  the  ridges  become  tubercu- 
lated,  the  venter  becomes  nmch  narrower  and  the  sides  also  tuberculated  and 
the  volutions  more  compressed.  These  spines,  nodes  on  the  casts,  are  in 
three  rows,  but  may  be  completely  absent  in  some  shells,  as  they  are  also 
in  some  old  shells.  In  old  age  the  venter  again  becomes  flattened  and 
smooth,  and  finally  broader  and  rounded. 

The  species  are  all  coimected  so  closely  by  intemnediate  forms  that 
distinct  lines  are  difficult  to  draw  between  contiguous  s])ecies. 

The  compressed  and  highly  involute  young  show  that  those  species, 
like  J',  f/iiadulupce,  having  depressed  volutions  with  broad  venters,  are 
senile  forms  in  the  ])hylum,  or  what  I  have  named  phylogerontic.     They 


PLACENT1CERAT1D.E.  '189 

are  not  scaphitoid,  as  stated  by  Muiiier  Chalmas,  except  in  the  sense  that 
ScaphUe.^  is  an  extreme  case  of  the  same  tendency  to  reproduce  senile  char- 
acters early  in  the  ontogeny  and  to  such  an  extent  that  tlie  ephebic  form 
becomes  more  or  less  influenced  by  them.  The  species  form  a  series,  there- 
fore, leadino-  ofl"  from  shells,  like  P.  sipiak  in  one  direction  into  P.  guada- 
lupe  and  in  the  other  into  wUtfieldl  The  intermediate  modifications 
connecting  this  genus  with  Protengonoceras  are  probably  partly  represented 
by  Diplaanocems,  but  this  genus  is  not  a  primitive,  although  it  seems  to  be  • 

a  i)hyloneanic  form. 

The  solution  of  the  species  problem  apiiears  to  lie  principally  in  the 
development  of  tubercles  and  the  correlative  stoutness  of    the  volutions. 
Shells  having  heavy  tubercles  in  three  lines  usually  also  have  sutural  pecul- 
iarities that  enable  one  to  distinguish  them.     The  peculiarities  of  the  gerontic 
stage  are  also  distinct,  as  will  be  noticed  in  the  descriptions.     In  some  spe- 
cies the  neanifc  stages  are  quite  distinct  in  their  sutures,  although  alike  in 
their  forms  at  the  same  age,  and  perhaps  with  more  materials  the  study 
of   these  and   the  development  of   sutures  may  give  good  results.     Hie 
most  highly  modified   form   as   compared    with    its   own   neanic   stage   is 
cevt-Am\y  guadaliipce,  but  although  the  sutures  are  complicated  in  outline, 
they  are  not  so  complex   as  those  of  whiffieldl,  and  the  modifications  ot 
form  are   distinctly  in  a   phylogerontic  direction.     The  varieties  of  each 
species  and  the  development  point  to  the  most  prevalent  syrtaloid  form 
as  presenting  more  than  any  other  purely  progressive  characters.     This 
form  has  moderately  compressed  involute  wlioris,  with  three  lines  of  nodes, 
narrow  venter,  and"  steadily  complicating  sutures.     The  same  variations  in 
the  species  and  in  the  individual  point  consequently  in  one  direction  toward 
(fuadalupcB  and  in  another  toward  whitfieldi.     This  last  is  reached  through 
si>ecies   like    stnntoni    and  pseiidophicenta,    in    which   the   median   lines  of 
tubercles  become    permanently   obsolete    and    the  outer  and    iimer   lines 
l^ecome  less  prominent   and   in  many  specimens  of  whitfieldi  are   absent. 
The  interesting  fact  in  this  connection  is  that  whitfieldi,  which,  as  compared 
with  its  own  young,  is  the  least  modified  of  all  the  forms,  has  the  largest 
shells,  the  least  affected  b)-  gerontic  degeneration,  and  at  all  stages  the 
most  complex  sutures. 

These  facts   also   show    in  a  marked  way  the  law  of  retardation  of 
development.     This  was  joined  by  Cope  with  acceleration,  but  so  far  as 


1 90        PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

my  experience  goes  they  are  quite  distinct.  Retardation  occurs  in 
cephalopods  in  phylogerontic  forms.  Thus  in  tliis  phylogerontic  genus 
the  A^oung  is  a  higlily  modified,  compressed  invohite  shell  in  the  neanic 
stage:  the  adult  in  some  species  Wke  ffuadalupfe  and  the  f>uro]3ean  depressum 
m;iy  have  additional  modifications  ending  with  a  paragerontic  stage  also 
tnbercnlated,  but  with  peculiar  broad  venter  and  lateral  nodes.  In  other 
species,  obviously  closely  connected,  like  jiseudosijrtale,  newberryi,  planum, 
•  and  European  congeners  like  grossouvrei  and  milleri,  the  first  appearance  of 
tubercles  occurs  later  in  tiie  ontogeny  and  they  are  present  in  their  full 
development  only  in  the  latest  ephebic  substage  or  gerontic  stage..  The 
same  law  holds  also  in  the  series  leading  from  syrtale  through  intercalare 
and  dantoni  to  ivhitfieldi.  In  some  forms  of  syrtale  and  intercalare  the 
three  lines  of  tubercles  appear  earfier  than  in  the  typical  forms  of  the  same 
species  and  in  placenta. 

In  stantoni  and  2)sendo2)lacenta  this  later  appearance  'of  tubercles 
becomes  invariable  and  correlates  with  the  disaiJpearance  of  the  centran 
line  and  a  tendency  to  decrease  in  size  of  these  ornaments  on  the  venter 
and  umbilical  shoulders. 

In  whitfieldi  this  tendency  results  in  the  total  disappearance  of  tlie 
tubercles  in  a  large  number  of  shells,  three  lines  of  tubercles  being  present 
only  in  a  very  few  shells  and  always  of  very  small  size,  plainly  individual 
reversions. 

The  sutures  are  simpler  in  outline  and  contiiuie  persistentlv  to  hold  the 
syrtaloid  outlines,  and  are  easily  separaljle,  except  in  extreme  age,  in  all  of 
the  guadalupan  series,  including  not  only  the  stouter  forms  like  gitadalupfc, 
but  the  highly  compressed  shells  like  planum.  In  tlie  series  leading  up 
to  ivhitfieldi  there  is  a  mai'ked  gain  Ijotli  in  com|)lexitv  of  outline  and  in 
gei'ontic  characters.  This  is  apparent  in  intercalare  and  placenta,  which  stjll 
retain  the  three  lines  of  tul)ercles,  and  is  still  more  })ronounced  in  stantoni 
and  pseudoplacenta  and  culminates  in  wJiitfieldi.  In  these  last  the  sutures  are 
similar  to  syrtale  only  in  the  neanic  stage,  and  in  whitfieldi  tliev  become 
more  rapidly  complex  in  ontogeny  than  in  other  species  and  overlaj)  to 
such  an  extent  that  it  becomes  more  difiicult  to  separate  them  throughout 
the  ephebic  and  gerontic  stages.  This  overlapping  is  a  purely  gerontic 
character,  and  the  species  that  show  it  during  the  ephebic  stage  are 
therefore  i)hyloge]-ontic    and  to    this  extent  degenerative   in    spite  of  the 


PLACENTICERATID.E.  191 

increase  in  complication  of  ontlines  of  the  lobes  and  saddles  and  their  large 
size.  This  phylogerontic  character  is  also  accompanied,  as  stated  above, 
by  loss  of  ornamentation  and  retention  thronghout  life  of  the  compress«Ml, 
involute,  smooth  volutions  of  the  neanic  stage. 

The  living  chambers  are  persistently  one-half  of  a  volution  in  length, 
whether  occurring  in  depressed  or  compressed  shells  or  in  dwarfs,  and  the 
apertures,  so  far  as  seen,  have  a  short,  l)lunt  vdstrum  and  low,  broad  lateral, 
crests. 

Grossouvre's  careful  descrijjtions  and  exceptionally  fine  figures  of 
the  difl^erent  forms  included  under  the  name  of  Placentkeras  syrtale  show 
that  while  there  exists  in  France  and  Gerinany  a  series  closely  parallel 
to  that  of  (/iiadahipce,  sancarlosense,  newberri/i,  pseudosyrtale,  and  planum  in 
this  country,  all  of  the  European  shells  present  differences  showing  that 
the  evolution  of  the  modifications  was  distinct  in  France.  The  gerontic 
stages  show  a  greater  tendency  on  the  part  of  the  imier  lines  of  nodes  to 
grow  farther  out  on  the  lateral  zones  and  approximate  to  the  venter,  and 
tlie  venter  not  only  fiattens  out  to  a  plano-convex  outline,  as  in  some 
American  species,  but  also  in  a  subsequent  gerontic  substage,  as  in 
P.  grossouvrei  and  miJIeri,  becomes  more  or  less  concave.  This  is  due  to 
the  increasing  size  of  the  tubercles  of  the  median  line  on  the  borders 
of  the  venter  after  the  disappearance  of  the  ventral  lines  of  earlier  stages. 

Kossmat"  sums  up  the  literature  of  the  genus  Placentkeras  and  its 
allies.  The  type  of  the  genus  Buchkeras  is  erroneously  considered  as  a 
species  of  SchloenbacJua.  Schloenhachia  is  a  genus  with  normal  outlines  to 
the  sutures,  a  decisive  keel  with  channels  or  smooth  bands  on  either  side, 
and  more  or  less  sigmoidal,  prominent,  well-developed  costae,  the  aperture 
having  a  long,  pointed  rostrum  correlating  with  the  keeled  venter.  The 
development  is  also  very  distinct  from  that  of  any  of  the  Pseudoceratites  of 
the  Cretaceous.  In  preceding-  pag-es,  B.  hilobatum  is  joined  with  other 
related  species,  and  the  differences  of  the  series  to  which  it  belongs  can  be 
more  readily  seen.  Kossmat's  strictures  with  regard  to  my  own  work  on 
this  group  are  just  and  most  of  his. objections  well  founded.  His  reference 
to  balduri  Keyserling,  as  the  probable  radical  of  Placentkeras  may  be 
correct.  At  any  rate  there  are  some  facts  that  favor  this.  The  sutures 
are  similar  to  those  of  Placentkeras.     The  young  of  this  species  certainly 

"Siiclinil.  Kreidef. :  Beitr.  Pal.  unci  Geol.  Osterreich-Ungarns  iind  des  Orients,  Vol.  IX,  189.5,  ji.  171. 


192.        PSErDOCERATITES  OF  THE  CRETACEOUS. 

I'esembles  tluit  of  some  of  this  oeniis  in  having  a  chamieled  venter,  but 
it  is  uuich  too  invohite  and  compressed  for  a  primitive  tvpe.  Tlie  keel 
of  halduri  is  devehiped  in  tlie  center  of  a  broad,  concave  venter  of  neanic 
age,  as  an  obtuse  raised  area,  l)ut  finally  the  entire  venter  becomes 
elevated  with  a  subacute  carina,  like  that  of  Buchiceras  A  raised  nascent 
keel  may  be  said  to  appear  at  a  late  age  in  some  species  of  I'Jarmticcras, 
but  the  venters  in  them  are  A'ery  narrow,  and  no  such  effect  is  produced 
as  in  halduri.  The  very  narrow  channel  of  the  ananeanic  stage  in  this 
species  and  the  late  development  of  the  tubercles  produce  resemblances 
to  Diplacmoceras,  but  in  this  genus  the  outer  lines  of  tubercles  are  not  on 
the  ridges  of  the  venter  as  the}'  are  in  halduri.  If  this  species  is  the 
ancestor  of  Diplacmoceras,  we  have  still  to  account  for  this  and  the  fact 
that  the  nepionic  stages  in  Placenticeras  exactly  match  those  of  Protengono- 
ceras  and  Knemiceras  and  are  never  keeled  as  in  Buchiceras  and  Boemeroce- 
ras.  So  far  as  Keyserling's  drawings  go,  the  nepionic  form  of  halduri 
before  the  channel  appears  is  like  that  of  Buchiceras  and  Tissotia  serrata. 

The  separation  of  the  genus  Placenticeras  from  the  Hoplitidae"  demands 
a  few  words  of  explanation.  Its  association  with  Hoplites  by  Douvilk'  and 
Grossouvre  depends  upon  the  connection  supposed  to  be  shown  by  the 
large  fii'st  lateral  saddle  of  HojjUtes  splendens.  This  saddle,  as  figured  by 
these  two  distinguished  authorities,  has  the  three  large  marginal  lobes  and 
three  saddles  which  are  supposed  by  them  to  be  homologous  with  the  tln-ee 
principal  laterals  of  Placenticeras. 

The  author's  position  is  quite  distinct  from  this.  If  the  three  marginals 
of  H.  splendens,  having  undoubtedly,  as  stated  by  them,  great  similarity  to 
the  principal  laterals  (first  to  third)  of  Placenticeras,  are  intermediate  grada- 
tions and  not  a  case  of  parallelism,  some  similar  stage  ought  to  be  present 
in  the  development  of  species  having  three  principal  laterals.  This,  so  fkr 
as  1  know,  is  not  the  history  of  the  development  in  any  form  of  this  kind. 

"It  is  disapiKiinting  and  much  to  be  regretted  that  no  direct  mention  is  made  of  Prof.  .James 
Perrin  Smith's  paper  on  Tlie  Devel(jpment  and  Phyiogeny  of  Pldfenticfrui:  (Proc.  Cal.  Acad.  Sci.,  3d 
series,  (ieol.,  Vol.  I,  pp.  181-240),  although  incidental  reference  to  it  is  made  in  connection  with 
the  <levelopment  of  the  sutures.  If  Professor  Hyatt  had  completed  the  revision  of  his  manuscript,  he 
woukl  doubtle.ss  have  reviewed  this  paper  and  made  some  dispositon  of  the  two  species  P.  •:i;cificuiit 
aniV  1'.  californicum,  treated  in  it.  Professor  Smith  concludes  that  Placerdicerax  was  derived  directly 
from  Ifoplilei:.,  but  the  two  species  whose  ontogeny  he  studied  differ  greatly  from  the  typical  forms  of 
Placentii'eriiy,  and  the  results  should  be  tested  by  a  comparative  study  of  some  such  forms  as  /'.  /ilncenta 
or  wbitJkhU.—'V.  \X .  S. 


PLACENTICEKATID.E.  193 

In  all  genera  having  but  one  principal  lateral  (HopUtes,  Schloenbachia, 
Buchiceras),  this  lateral  is  a  direct  and  closely  connected  modification  of  the 
primitive  lateral  of  the  young.  Also  in  genera  having  two  or  tln-ee  saddles 
these  are  not  preceded  by  an  intermediate  stage  in  which  one  large  lateral 
arises  like  that  of  Schhenhachia  and  HopUtes  splendens,  but  on  the  contrary, 
these  principal  laterals  arise  through  the  continuous  growth  of  the  two  or 
tln-ee  primitive  and  more  or  less  tongue-shaped  and  at  first  entire  mar- 
ginals that  develop  in  the  top  of  the  primitive  first  lateral  lobe,  as  has  lately 
been  shown  by  J.  Perrin  Smith. 

When  these  are  arrested  in  development  and  do  not  increase  in  com- 
plexity and  remain  entire  or  become  simply  bifid  or  trifid,  etc.,  the  differen- 
tiation between  them  and  the  auxiliaries  is  lost  and  the  sutui'es  of  the  adult 
are  similar  to  those  of  the  Engonoceratida?  and  the  like.  When,  however, 
these  do  acquire  more  complex  outlines  and  the  development  is  duly  pro- 
gressive, its  effect  is  invai-iably  and  naturally  greater  upon  the  saddles  and 
lobes  of  the  outer  side,  which  have  free  growth  and  are  most  called  upon 
to  help  hold  the  animal  in  the  shell.  These,  either  on  this  account  or  for 
some  other  reason  as  yet  iinknown,  certainly  during  development  as  a  rule 
become  more  complex  than  the  inner  laterals.  This  complexity  is,  as  a  rule, 
less  in  direct  proportion  to  the  distance  of  the  saddle  or  lobe  from  the 
periphery  if  an  allowance  be  made  for  the  natural  division  due  to  the  greater 
or  less  persistence  and  sometimes  moi'e  or  less  independent  development  of 
the  largest  lateral  lobe.  This  is  the  primitive  first  lateral  in  normal  forms, 
but  in  retrogressive  genera  it  may  be,  as  in  Placenticeras,  the  third  marginal 
lobe  of  the  primitive  first  lateral,  as  has  also  been  shown  by  Smith.  This 
greater  development  can  be  accounted  for  by  the  greater  stress  of  the  muscles 
at  these  median  parts  in  balancing  the  shell  while  crawling.  It  interferes 
with  the  regulanty  of  the  gradations  in  size  and  complexity  of  the  series, 
and  marks  the  division  between  the  principal  or  larger  lateral  lobes  and 
saddles  and  the  so-called  auxiliaries. 

In  most  gi'oups  of  Ammonitina;  the  first  lateral  becomes  bifid  and  the 
centran  marginal  lobe  is  the  first  that  appears.  Usually  the  next  saddle  to 
become  bifid  is  the  first  auxiliary.  This  occurs  in  Placenticeras,  while  the 
second  and  third  laterals  still  have  entire  bases.  In  other  words,  similar 
laws  govern  the  development  of  the  two  series  of  saddles,  the  principal 
laterals  and  the  auxiliaries,  so  far  as  the  development  of  the  first  saddle  of 
MON  XLIV — 03 13 


194  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

each  series  is  concerned.  Subsequently,  however,  there  is  more  irreguLirity. 
Thus  the  second  auxihary  is  not  necessarily  the  next  to  become  bifid,  but 
it  is  apt  to  be  the  next,  and  the  process  passes  inward,  the  innermost  saddles 
being  usually  the  last  to  become  bifid,  but  tliere  is  great  irregularity  in  the 
first  appearance  of  l)ifidity  or  division  among  the  auxiliaries. 

As  a  rule,  however,  this  irregularity  does  not  occur  in  the  innermost 
saddle,  which  is  often  broad  and  remains  entire  later  than  its  neighbors 
and  is  the  last  to  show  complications  of  outline. 

The  second  and  third  of  the  principal  saddles  in  Placenticeras  appear 
to  reverse  this  law  of  pi'ogress  inward.  After  the  first  has  advanced  to  the 
trifid  stage,  it  is  the  third  which  leads  in  complication  of  outline  and  the 
second  which  comes  next.  This  same  reversion  is  found  also  in  the 
principal  lobes  In  this  genus  the  primitive  lateral  lobe  is  continuous  in 
develojiment  with  the  third  lateral,  and  it  is  this  that  first  shows  the  trifid 
division,  which  is  the  incipient  stage  of  complication;  then  the  second 
follow,  and  after  this  the  first.  The  last  two,  however,  may  progress  in 
nearly  equal  ratio. 

The  second,  third,  and  fourth  auxiliary  lobes  are  apt  to  follow  the 
lead  of  the  first  auxiliary  in  regular  succession,  but  there  is  variation  in  this 
respect,  as  among  the  saddles.  The  general  law,  however,  is  the  same  as 
among  the  saddles,  the  innermost  being  the  last  to  modify  their  entire 
primitive  outlines. 

In  the  development  of  the  sutures  there  are,  however,  two  series  to  be 
considered,  first  the  products  of  the  development  of  the  first  primitive 
lateral  saddle  of  the  nepionic  stage,  and  second  the  products  of  the  inflec- 
tions in  outline  of  the  second  primitive  lateral  saddle.  These  form  two 
series  of  lobes  and  saddles  on  either  side  of  the  primitive  fii-st  lateral  lobe 
and  obey  diff'erent  laAvs  of  development.  The  complication  in  the  lobes 
proceeds  from  the  oldest  lobe,  the  primitive  first  lateral,  outward  and 
inward;  the  complication  in  the  saddles  begins  with  the  primitive  first 
lateral  and  proceeds  inward  when  that  saddle  is  not  divided  in  the  neanic 
stage.  When,  however,  that  saddle  is  divided  into  three,  there  is  more  or 
less  irregularity  in  the  progression  in  complexity  of  the  outlines  of  the 
second  and  third  saddles.  The  outer  division  or  principal  first  lateral  is, 
however,  apparently  always  the  one  that  grows  fastest  and  leads  off  in 
acquiring  a  more  complex  outline,  as  may  be  observed  in  about  all  ot  the 


genera  noted  below. 


PLACENTICERATID.E.  195 

The  tendency  of  the  saddles  to  become  bifid  in  their  first  stage  of 
compHcation  was  noted  by  Branco  and  since  by  Nickles,  lint  in  the  lobes 
this  varies.  In  these  the  first  stage  of  complication  is  apt  to  be  either  bifid 
or  trifid,  according  to  the  form  of  the  entire  lobe  of  the  preceding  stage. 
If  these  be  pointed,  the  next  step  in  complexity  is  the  formation  of  a  trifid 
top,  if  they  be  rounded  or  flattened,  the  next  grade  is  usually  a  bifid 
termination. 

In  the  genera  described  below  there  is  a  notable  tendency  toward  the 
formation  of  trifid  lobes  in  all  of  the  oiiter  lobes  and  in  a  number  of  the 
auxiliary  series,  the  inner  and  last  auxiliary  lobes  showing  a  tendency  to 
become  bifid. 

The  saddles  and  lobes  in  any  one  suture  of  the  genera  which  have 
arrested  development  of  the  lobes  and  saddles,  and  even  in  some  like 
Sphenodiseus  and  Placenticeras  with  very  complex  outlines,  show  a  graded 
series  of  modifications  from  the  line  of  involution  outward.  These  have 
frequently  such  simple  entire  lobes  and  saddles  near  the  umbilicus  that  one 
can  see  at  a  glance  that  they  are  like  the  entire  outer  lobes  and  saddles  of 
the  young.  The  suture,  in  fact,  presents  a  series  of  modified  forms  that 
show  in  a  general  way  the  history  of  the  development  of  any  one  of  the 
outer  lobes  or  saddles,  if  it  be  traced  from  its  entire  stage  to  the  suture 
wliich  is  being  observed.  This  is  due  to  the  fact  noted  above  and  also 
shown  in  Branco's  observations  and  the  author's  on  the  young,  viz,  that 
new  lobes  and  saddles  as  a  rule  are  added  from  the  line  of  involution  so 
that  these  in  any  extended  suture  line  are  younger  or  later  introdiu-tions. 
In  some  genera  with  aiTested  development  these  remain  comparatively 
unmodified,  but  in  most  genera  of  Ammonitina?  and  in  Placenticeras  these 
do  become  modified  and  have  complex  outlines  in  later  stages,  althouo-h 
never  so  complex  as  in  the  outer  saddles  and  lobes.  When  this  modifica- 
tion by  development  takes  place  these  internal  and  younger  lobes  and 
saddles  proceed  or  develop  by  repeating  the  stages  passed  through  by 
their  outer  and  more  rapidly  developed  companions  of  the  same  sutures. 

In  other  words,  the  lobes  and  sutures  of  Ammonitinpe  exhibit  the  same 
law  of  repetition  or  jiarallelism  in  local  development  which  was  first 
discovered  by  Dr.  R.  T.  Jackson  among  the  Echinoids.  He  there  showed 
that  a  newly  introduced  plate  of  the  corona  passed  through  stages  of 
modification  in  the  course  of  its   subsequent  growth  which  were  parallel 


196  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

with  those  which  had  already  been  passed  through  Ijy  the  surrounding 
plates  of  the  corona  during  the  stages  of  the  ontogeny. 

In  other  words,  there  is  a  local  ontogeny  in  newly  introduced  lobes 
and  saddles  parallel  with  the  developmental  ontogeny  of  the  same  elements, 
and,  in  growing,  each  newly  introduced  internal  lobe  or  saddle  repeats 
locally  the  same  stages  of  development.  The  arrest  of  development,  whicli 
takes  place  habitually  in  all  forms  of  Ammonitina?,  internally  stops  the 
progress  of  each  lobe  and  saddle  at  different  stages  in  proportion  to  the 
distance  of  the  lobe  or  saddle  of  the  auxiliary  series  from  the  line  of  involu- 
tion. In  genera  like  Engonoceras,  however,  the  entire  suture  is  arrested  in 
development  and  presents  therefore  a  certain  resemblance  to  the  young  of 
other  Ammonitinse  in  the  neanic  stage  and  especialh'  to  the  young  of 
PlacenUceras  after  the  three  entire  principal  lobes  and  saddles  and  the  entire 
lobes  and  saddles  of  the  auxiliary  series  have  appeared.  It  may  be  objected 
that  the  division  between  the  species  is  too  minute  and  artificial,  and  it  is 
admitted  that  this  objection  is  in  one  sense  well  founded. 

There  is  no  real  line  between  P.  guadalupce,  sancarlosense,  and  i^lanum, 
nor  between  newherryi  and  guadalupcB,  nor  between  guadalupce,  sancarlosense, 
sgrfale,  intercalare,  and  placenta,  nor  between  intercalare,  stantoni,  pseudopla- 
centa,  and  ivhitfieldi.  As  a  matter  of  fact  there  is  no  real  break,  such  as  is 
usually  supposed  to  establish  a  species,  between  P.  guadalupce  and  the 
extreme  form  of  wJdtfieldi. 

If,  however,  one  admits  that  all  American  forms  make  up  only  one 
species,  it  becomes  illogical  to  sepai-ate  the  European  forms  from  each 
other  or  the  American  from  them,  and,  consequently,  all  the  forms  of 
PlacenUceras  are  one  species. 

I  have  not  been  able  to  find  any  middle  ground  between  these  two 
extremes,  but  have  found  that  it  is  possible  to  diagnose  species  by  describing 
the  normal  forms,  meaning  thereby  the  shells  that  are  most  distinct  and 
usually  most  numerous  in  each  species,  and  adding  thereto  the  mention  of 
intermediate  forms. 

When  this  is  done,  it  is  seen  that  in  this  genus  the  separable  forms  or 
species  can  be  distinguished  by  their  differences  in  development  of  the 
sutures,  of  identical  oi'naments,  and  of  the  sectional  outlines  of  the  volutions. 
The  changes  that  take  place  in  the  aspect  of  the  venter  and  of  all  characters 
in  the  senile  or  gerontic  stage  are  included  under  the  term  development, 
which  in  the  sense  here  used  means  all  tlie  modifications  of  the  ontogeny. 


PL  ACENTICERATID.E.  197 

Elacenticeras  GUADALUPE"  (Roemer). 

PI.  XXIX,  tigs.  1-4. 

Ammonites  guadolupse  Roemer.  1853,  Kreideb.  v.  Texas,  pi.  2. 

The  best  specimen  I  have  seen  has  a  diameter  of  aliout  145  mm.  Outer 
volution  on  gerontic  living-  chamber  about  halfway  to  the  aperture  is  63 
mm.  and  trausvei'se  diameter  47  nun.,  the  same  volution  opposite  is  43  mm., 
the  transverse  being  34  mm.,  avoiding  the  tubercles.  The  umbilici  are 
deeper,  the  umbilical  zones  being  more  rounded  and  the  involution  greater 
than  in  pseudosiirtale.  The  involution  covers  the  iimer  volutions  to  the  inner 
line  of  tubercles,  whereas  in  pseudosyrtale  these  are  not  only  completely 
uncovered  but  well  inside  of  the  line  of  involution.  The  venter  is  very 
broad,  so  that  the  second  lines  of  tubercles  are  on  its  lateral  angles  and  the 
first  lateral  saddles  and  lobes  are  oh  the  ventral  aspect.  The  alternating- 
ventral  tubercles  and  the  flat  ventral  zone  between  them  are  retained  on  the 
venter  tln-oughout  the  ephebic  stage.  The  inner  row  consists  of  large 
acute  spines,  solid  at  the  tii)s  only,  which  are  large  nodes  on  the  cast,  at 
the  start  when  the  umbilicus  is  only  25  mm.  in  diameter.  These  recede 
outwardly  with  age,  but  remain  more  prominent  than  in  pseudosyrfule  at  the 
same  age  and  the  inner  ridges  are  also  much  larger.  The  aperture  is 
partly  preserved  and  is  apparently  at  the  end  of  the  metagerontic  substage, 
judging  by  the  last  sutures,  which  are  not  closely  approximated,  and  by 
the  aspect  of  the  last  tubercles.  The  margin  of  the  aperture  has  a  sinus 
near  the  line  of  involution  and  broad  lateral  crest,  but  beyond  this  it  could 
not  be  seen.  The  venter  is  convex  and  elevated  in  the  gerontic  stage  and 
had  a  ventral  zone  as  described  above.  The  volutions  are  stouter  at  all 
stages  than  in  jisciidosyrtale.  Having  broken  open  this  specimen,  it  was 
ascertained,  as  I  had  expected,  that  the  young  is  more  compressed  and 
slender  than  the  outer  volutions,  although  in  most  Ammonitina"  the  reverse 
of  this  is  true.    The  rounded  nepionic  volutions  were  followed  as  in  other 

"  Mr.  T.  W.  Stanton  has  courteously  commented  as  follows  upon  this  species: 
"The  original  spelling  'guadalupie'  should  be  restored.  The  name  of  the  river  is  'Guadalupe.' 
The  type  locality  should  be  given  'Waterfall  of  the  (TuadaUipe  Vielow  New  Braunfels'  where  the  only 
hiirizons  represented  are  the  top  of  the  Austin  limestone  and  the  lower  part  of  the  Taylor  beds.  The 
specimens  from  .San  Carlos  are  from  Ijeds  proliably  of  about  the  same  age  in  a  formation  to  which  Mr. 
Hill  has  given  the  local  name  San  Carlos  beds.  The  Fort  Worth  locality  [alluding  to  the  specimen 
with  that  locality  in  my  collection]  must  be  inaccurate,  as  there  are  no  I'pper  Cretaceous  beds  within 
several  miles  of  that  place." 


198        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

species  by  the  compressed    and  deeply  involute  volutions  of  the  neanic 
stage,  and  these    acquired  first  the    flattened  venter    and  helmet-shaped 
section  and  then,  as  the   ventro-dorsal   diameters  leng-thened,  the  hollow 
venter  bordered  by  smooth  ridges  and  general   aspect  of  Protengonoceras. 
The  facts  were  ascertained  13}^  excavation  as  well  as  liy  studying  the  section. 
Unluckily  the  sutures  were  nowhere  exposed  in  these  inner  volutions. 
The  auxiliaries  were  visible  later  in  the   neanic   stage  after  the  volutions 
had  become  more  compressed.     They  were  then  of  the  syrtale  type,  but 
their  simple  outlines  showed  that  in  the  preceding  Protengonoceras  age  they 
must  have   been  very  simple  in  outline   and   perhaps  similar  to  those  of 
Engonoceras.     Tlie  nodes  on   the   cast  did  not    begin    to    appear    on  the 
umbilical  shoulders  until  the  shell  was  about  35  to  40  mm.  in  diameter  and 
had  entered  upon  the   ephebic  stage.     The  outer  row  of  spines  were  not 
■\-isible  until  later,  and  the  age  at  which  they  appeared,  except  that  it  was 
later  than  the  neanic  stage,  could  not  be  ascertained.     The  ephebic  stage 
has  a  stout  volution  with  gibbous  sides  with  proportions  entirely  different 
from  those  of  the  gerontic  stage.     At  diameter  of  2G   mm.  from   line  of 
involution  to  venter  the  transverse  diameter  at  umbilical  shoulders  is  15  mm. 
and  at  6  ram.  distant  from  the  venter  the  transverse  diameter  is  11  mm.     The 
lateral  zones  are  nearly  flat  and  only  slightly  convergent  and  then  converge 
rapidly  but   convexly  to  the  venter  which  is   broad,  being  here  5  mm. 
The  last  part  of  the    neanic  stage  is   11.5    by  5    mm.  at    the    umbilical 
shoulders  and  the  convergence  of  the  faintl}-  convex  lateral  zones  outwardly 
is  constant  to  the  venter,  which  is  1.5  mm.  in  breadth.     The  gerontic  v(^lu- 
tion  on  same  section  is  45.5  by  35.5  mm.  at  the  umbihcal  shoulders  and 
between   tubercles;    the  piano  convex  venter  is   27.  5  nun.,  also   between 
tubercles.     The  ventral  line  of  tubercles  and  the  concave  area  or  ventral 
zone  disappears  in  the  gerontic  stage,  and  the  last  measurements  were  taken 
after  their  disappearance  near  the  basal  sutures  of  the  living  chamber. 

Roemer's  figures  are  excellent,  but  they  show  a  specimen  much  larger 
than  mine,  and  but  just  entering  the  anagerontic  substage.  Roemer  esti- 
mated that  his  shell,  when  complete,  must  have  been  a  foot  in  diameter. 

The  living  chamber  of  Roemer's  specimen  was  broken  away,  or  it 
would  have  shown  similar  gerontic  characters.  There  is  a  centran  trace  on 
the  venter  of  Roemer's  figure  which  is  present  also  on  the  venter  of  the 
ephebic  stage  hi  my  cast.     The  trace  is  double,  consisting  of  a  taint  depres- 


PLACENTICEKATID.E.  199 

siou  between  equally  faint  ridges.  There  is  also  a  faint  trace  on  the  venter 
of  the  neanic  stage,  but  it  is  then  a  single  line  sunk  in  the  surface  of  the 
shell.  It  is  too  faint  to  be  visible  in  any  section,  and  is  probably  not  present 
in  the  younger  stages. 

In  the  neanic  stage  the  rather  large  siphuucle  is  at  a  perceptible  distance 
from  the  shell  of  the  venter,  but  in  the  ephebic  stage  it  is  directly  against 
it,  and  the  double  trace  may  be  due  to  this. 

The  sutures  ai-e  more  widely  separated  in.Roemer's  figure  tlian  in  n^y 
specimen,  but  this  may  be  due  to  more  vigorous  growth.  There  were 
eleven  saddles  and  ten  lobes  on  the  older  sutures,  with  less  complicated 
outlines  than  in  pseudosyrtde,  but  otherwise  similar.  The  sutures  are  well 
separated  at  all  stages,  but  the  last  two  are  nearer  together  than  the  preced- 
ing. The  ventral  lobes  are  deeper  and  narrower  and  the  siphonal  saddles 
more  prominent  and  distinct  than  in  other  species,  except  that  described 
by  Choffat  ni  Portugal  as  P.  uhligi.  It  stands  between  this  primitive  form 
and  P.  i).sni(los>jrtaJe  and  other  American  species,  all  of  wliicli  have  very 
broad  ventral  lobes  and  less  prominent  siphonal  saddles. 

A  very  fine  suite  of  this  species  was  collected  by  Stanton  and  Vaughan, 
locality  1467,  United  States  Geological  Survey,  San  Carlos,  Presidio 
County,  Tex.  The  largest  specimen  is  204  mm.  in  diameter;  a,  part  of  the 
aperture  at  the  umbilical  zone  shows  on  one  side  and  the  length  of  the  liv- 
ing chamber  is  somewhat  less  than  one-half  of  a  volution.  The  gerontic 
stage  is  present  and  the  involution  is  considerably  decreased  along  the  outer 
sides  of  the  nodes  on  their  retreat  from  the  umljilicus.  The  venter  becomes 
broader  and  rounded  on  the  last  part  of  outer  volution.  The  outer  nodes 
change  from  round  spines  to  elongated  costae,  dichotomous  with  the  inner 
line  of  nodes  that  are  nearly  at  the  middle  of  the  lateral  zones  at  this  ao-e. 

There  are  some  more  compressed  specimens  that  still,  however,  have 
very  stout  volutions  and  a  prolonged  stage,  during  which  the  venter  l^ecomes 
broadened  and  occupies  the  space  between  the  second  rows  of  nodes,  the 
outer  ventral  rows  forming  lines  on  either  side  of  a  zone  occupying  the 
center  of  the  ventral  surface.  These  features  are  still  like  those  of  typical 
guadalupcB,  but  in  other  cases  it  is  impossible  to  say  whether  the  specimens 
belong  to  typical  guadnlup(B  or  to  the  next  described  species. 

Loccditij:  San  Carlos,  Presidio  County,  Tex. 
Age:  San  Carlos  beds,  Upper  Cretaceous. 


200        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Placenticeras  sancarlosense  11.  sp.  Hyatt. 
PI.  XXX,  %s.  1-3:  PI.  XXXI,  figs.  1,  2. 

This  is  repi'esented  by  a  senes  of  specimens  in  collections  made  by 
Stanton  and  Vaughan  that  fade  into  trne  guadalupce. 

The  typical  forms  differ  in  liaving  smaller  tubercles,  the  compressed 
stage  is  more  prolonged  and  the  ephebic  volutions  are  never  so  stout  nor 
the  venter  so  broad  as  in  f/itndalup(e.  The  stage  in  which  the  venter  is 
broad  and  bounded  by  the  second  line  of  nodes  and  similar  to  that  of 
(juadalupm  is  short  and  is  often  distinctly  confined  to  the  anagerontic 
substage.  Some  of  the  specimens  of  this  form  are  very  closely  similar  to 
P.  si/rtale.  This  last  species  has,  however,  so  far  as  known,  no  stage  in 
which  the  venter  resembles  that  of  fiuadalupce,  i.  e.,  in  which  the  venter 
becomes  broadened  out  while  the  ventral  lines  of  tubercles  and  the  lateral 
nodes  are  still  preserved  in  nearly  their  full  development.  This  form  is 
obviously  an  exact  parallel  with  the  P.  pseudosijrtale  said  to  be  found  at 
Fort  Worth,"  liut  from  this  it  is  separable  by  the  involution  which  is  more 
considerable  and  follows  the  inner  line  of  tubercles.  There  are  dwarfs 
belonging  to  this  species  which  have  more  pronounced  tuberculations  than 
Placenticeras  neivherryi,  but  these  approximate  very  closely  to  the  specimens 
from  Presidio  del  Norte,  and  show  that  these  last  are  really  another  grade 
of  modifications  having  the  same  general  tendency. 

Locality:  San  Carlos,  Presidio  County,  Tex. 

Age:  San  Carlos  beds.  Upper  Cretaceous. 

Placenticeras  sancarlosense  variety  pseudosyrtale  Hyatt. 
PL  XXXII;  PI.  XXXIII.  fig.  1. 

The  type  of  this  variety  is  a  well-pi'eserved  cast  200  mm.  in  whole 
diameter.  The  last  -v^olution  from  lines  of  involution  to  venter,  although 
mucli  affected  by  senile  contraction,  is  80  mm.  and  the  same  volution  oppo- 
site is  65  mm.  The  veutro-dorsal  diameter  is  73  mm.  about  half  way  the 
length  of  the  living  chamber,  and  the  transverse  diameter  is  53  mm.,  avoiding 
the  tubercles.  The  same  ventro-dorsal  diameter  at  last  septum,  taken 
always  from  line  of  involution  to  venter,  is  63  mm.  and  the  transverse, 
avoiding  the  tubercles,  is  43  mm.     The  tubercles  of  first  inner  row  alternate 

o  See  note  on  p.  202. 


PLACENTICEKATID.E.  201 

with  those  of  the  opposite  side ;  the  outer  vow  is  more  luimerous  than  the 
iuner,  and  there  are  shght  indications  of  bifurcated  ridges  of  costfe  con- 
necting them  on  the  cast.  The  ventral  tubercles  are  irregularly  alternate 
with  the  second  row  and  there  may  have  been  ridges  bifurcating  more  or 
less  between  these,  but  there  are  no  indications  of  these  on  the  cast. 

It  is  very  like  Morton's  species,  but  the  gerontic  stage  begins  later  and 
the  increase  of  the  ventro-dorsal  diameters  is  much  more  rapid.  The  width 
through  the  umbilical  shoulders  is  greater  at  the  same  age  and  the  lateral 
zones  flatter  and  more  convergent,  owing  to  the  greater  prominence  of  the 
umbilical  shoulders.  The  ventral  lines  of  tubercles  are  more  elongated, 
not  so  close  together,  and  quite  different,  and  the  second  inner  line  of  tuber- 
cles is  less  prominent  and  nearer  to  the  vertical  lines.  The  inner  lines  ot 
tubercles  do  not  appear  until  the  ephebic  stage  and  are  at  first  very  minute 
but  rapidly  enlarge  in  the  remainder  of  the  ephebic  and  gerontic  stage, 
disappeaiing  suddenly  before  the  outer  ones  at  the  beginning  of  the  para- 
gerontic  substage.  They  recede  from  the  umbilical  shoulders  outwardly  in 
the  23ai"ephebic  and  gerontic  stages  and  have  an  inner  costation  or  ridge 
inclined  ajjicad. 

The  outer  line  of  tubercles  disappears  in  the  paragerontic  substage 
immediately  after  the  inner  line.  The  ventral  lines  of  tubercles  disappear 
on  the  cast  in  the  metagerontic  substage.  These  tubercles  are  present  on  a 
bit  of  the  thick  ventral  shell  in  the  ephebic  stage.  These  are  almost  linear, 
alternating  and  widely  separated,  and  border  a  slightly  concave  ventral 
zone,  which  is,  however,  flat  upon  the  cast  at  the  same  age.  The  ventral 
zone  continues  well  defined  and  flat  upon  this  cast  until  quite  close  to  the 
aperture  in  the  extreme  of  the  paragerontic  substage.  The  contraction  of 
the  gerontic  volution  is  very  marked,  beginning,  even  in  the  parephebic 
substage,  before  the  gerontic  septa  appear  and  apicad  of  the  base  of  the 
gerontic  living  chamber. 

The  sutures  have  the  aspect  of  those  of  sijrtalc,  but  the  outlines  are 
more  complex  and  the  third  lateral  lobes  longer  and  more  pointed. 
This  does  not  appear  to  be  due  to  greater  age,  but  correlates  with 
the  larger  size  and  other  differences  in  the  form  and  development  of  tins 
specimen.  There  are  eleven  lobes  and  twelve  saddles  on  each  side  in  ana- 
gerontic  septa;  the  innermost  saddle  is  narrow  and  apparently  entire,  all 
the  remainder  divided  and  bifurcate  except  the  first  laterals.     In  these  the 


202  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

iuuer  arm  extends  inwardly  and,  being  itself  bifurcated,  gives  a  trifurcated 
aspect  to  each  of  these  saddles.  The  inner  lobes  are  bifurcated  and 
broaden  outwardly,  being  somewhat  lilunt  or  rounded  except  in  the  third 
lateral,  which  is  pointed  and  apparently  of  the  bifurcated  type,  as  are  also 
the  other  lobes.  The  last  four  sutures  are  moi'e  or  less  approximated,  and 
the  last  two  and  part  of  the  third  interfere,  as  in  P.  placenta,  except  near  and 
on  the  ^-enter. 

The  living  chamber  is  one-half  of  a  volution  in  length.  The  outer 
part  of  the  aperture  is  preserved,  showing  a  blunt,  broad,  rounded  ventral 
crest,  or  slight  rostrum,  ventro-lateral  sinuses  on  the  second  line  of 
tubercles,  and  the  appearances  indicate  broad  lateral  crests,  but  the  margins 
were  broken  away  inside  of  this.  The  approximation  to  P.  scmcarhsense  is 
so  close  that  probably  most  paleontologists  will  prefer  to  consider  them 
identical,  l)ut  the  lateral  nodes  are  larger  and  moi-e  quickly  developed  and 
the  ventral  tubercles  more  elongated  and  more  widely  separated.  The 
extremelv  thick  shell  is  shown  as  well  as  the  fact  that  the  ventral  tubercles 
are  not  more  prominent  on  the  thick  shell  than  they  are  on  the  cast. 

Locality:   Fort  Worth,  Tex." 

Af/e:   Probably  same  as  guadcdiqm  and  sancarlosense. 

Placenticeras   planum  n.  sp.  Hyatt. 
PI.  XXXIII.  tigs.  2-4:  PI.  XXXIV. 

This  is  also  a  part  of  the  collection  made  by  Stanton  and  Vaughau. 
This  species  also  grades  into  P.  sancarlosense  although  very  distinct  from 
(fnadalupce.  The  sides  are  almost  smooth,  the  tubercles  being  verj-  small 
and  obscure,  except  in  the  umbilicus.  The  affinities  for  (juadcdupce  and  its 
aUies  are  demonstrated  by  Mr.  Stanton's  care  in  collecting  this  line  series. 
The  flat,  compressed  aspect  of  tlie  young  is  maintained  until  the  shells  reach 
a  diameter  of  "221  mm.,  and  the  venter  does  not  show  any  Ijroadening  out 
until  after  the  shell  reaches  the  gerontic  stage. 

One  of  the  specimens  from  Presidio  del  Norte,  No.  21651,  is  240  mm.  in 
diameter.  Four-tifths  of  the  outer  volution  is  in  the  gerontic  stage,  but  the 
first  piu-t  of  the  pare))hebic  substage  shows  the  venter  still  narrow,  flat,  and 
tuberculated.     It  then  becomes  rounded,  but  the  volution  still  remains  com- 


"Mr.  Stantou  has  commented  as  follows  upon  this  alleged  locality:  "P.  mncarlosense  var. 
pseiidosyrtale,  labeled  '  Fort  Worth,  Texas,'  must  have  come  from  some  other  place,  though  possibly 
in  that  region."     (See  note  on  P.  ijucKlolupa.) 


PLACENTICERATID.E.  203 

pressed.  There  are  small  tubercles  in  the  umbilicus  but  these  disappear  in 
the  older  stages,  and  almost  the  entire  outer  volution  is  smooth.  The  other 
specimen  has  similar  characters,  and  tlie  sutures  are  of  the  fiuadalupce  and 
syrtale  type. 

This  species  is  not  separal)le  in  some  varieties  from  P.  neirhrrri/i,  except 
by  the  absence  of  large  lateral  nodes  at  all  stages. 

LocaUtij:  San  Carlos,  Presidio  County,  Tex.;  Presidio  del  Norte, 
Mexico. 

Age:  San  Carlos  beds.  Upper  Cretaceous. 

Placenticeras   newberryi  n.  sp.  Hyatt. 
PI.  XXXI.  tigs.  3-.X 

The  type  is  a  cast  with  small  patches  of  shell.  Diameter  is  120  mm., 
to  which  must  be  added  perhaps  5  mm.  for  depression  of  outer  volution. 
The  diameter  of  the  whole  coil  one-fourth  of  a  volution  younger  and  not 
altered  by  depression  is  94  mm.  The  outer  volution  at  aperture  is  54  mm. 
and  transverse  is  39  mm.,  the  umbilicus  is  24  mm.  and  the  opposite  part  of 
same  volution  is  42  mm.  and  transverse  28  mm.  The  last  volution  begins 
with  transverse  diameter  of  19  mm.,  enlarges  in  the  next  quarter  of  a 
volution  to  28  mm.,  and  just  beyond  this  the  large  gerontic  tubercles  begin. 
The  transverse  diameter  continues  to  increase  until  the  last  quarter  apicad 
of  the  aperture  is  reached,  and  then  it  diminishes  between  the  two  last 
tubercles,  which  are  wideh-  separated,  and  still  further  diminution  takes  place 
at  the  aperture.  In  another  specimen  there  is  no  diminution  in  the  rate  of 
growtli  of  the  transverse  diameter  apparent  to  the  eye,  but  this  specimen 
has  not  a  complete  living  chamljer.  The  almost  scaphitean  aspect  of  the 
liAang  chamber  in  some  specimens  is  misleading  and  is  in  part  due  to 
depression.  Nevertheless,  this  only  exaggerates  the  gerontic  metamorphoses 
of  this  interesting  species.  Small  nodes  are  present  in  an  early  ephebic 
substage  on  the  umbilical  shoulders  and  continue  to  increase,  becoming 
veiy  large  suddenly  in  the  anagerontic  substage.  Elongated  tubercles  are 
present  on  either  side  of  the  venter  in  the  ephebic  stage,  but  the  age  of 
introduction  was  not  ascertained;  apparently  it  is  later  tha*n  that  of  the 
tubercles  on  the  umbilical  shoulders. 

The  latter  are  widely  separated  at  all  stages,  but  the  ventral  tubercles 
are  close  together.     There  are  very  obscure  fold-like  costae,  some  of  them 


204        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

(liehotoiiious,  on  the  outer  part  of  the  outer  volution  on  the  cast,  but  these 
liave  no  perceptible  middle  row  of  tubercles  in  the  ephebic  stage.  The 
venter  increases  in  the  gerontic  stage  from  being  5  mm.  wide  between  the 
lines  of  tubercles  to  20  mm.  on  the  first  half  of  the  outer  volution,  and  this 
continues  to  grow  broader  and  more  convex  until  near  the  aperture,  where 
there  is  an  apparent  diminution.  As  the  venter  broadens,  the  costse  are 
brought  to  the  edges  of  the  venter  and  theii-  terminations  become  enlarged 
into  rows  of  nodes  as  the  geroutic  stage  progresses,  but  disappear  hi  the 
paragerontic  substage  as  the  venter  broadens  and  the  sui-face  of  this 
becomes  smooth  on  the  casts. 

The  living  chamber  is  somewhat  less  than  one-half  of  a  volution  in 
length.  It  has  very  deep  sinuses  on  the  umbilical  zones  and  prominent 
lateral  crests.  The  form  of  the  ventral  margin  was  not  seen.  The 
umbihcus  is  deep,  the  internal  volution  visible,  the  umbilical  shoulders  are 
prominent,  and  the  umbilical  zones  are  steep  and  broad,  as  in  other  species 
of  this  genus,  from  a  comparatively  early  age. 

The  sutures  are  of  the  guadalupaean  syrtale  type  and  well  separated, 
becoming  approximated  only  in  extreme  age.  There  is  only  one  change, 
however,  of  considerable  interest  in  the  gerontic  stage  due  to  the  broaden- 
ino-  out  of  the  venter.  The  ventral  lobe  does  not  broaden  in  the  same 
proportion,  and  consequently  in  this  stage  the  first  pairs  of  saddles  and 
finally  first  lateral  lobes  become  included  within  the  outer  line  of  tubercles, 
thus  becoming  transferred  to  the  venter,  as  in  P.  f/uadalupce.  Another 
specimen  (No.  11975  a)  from  the  .same  locality  is  more  compressed,  has 
somewhat  less  prominent  tubercles,  and  not  so  deep  umbilicus.  In  the 
interior  of  the  type  specimen  the  venter  of  the  later  part  of  neanic 
stao-e  with  shell  on  is  exposed.  This  shows  the  usual  compressed  form 
of  this  stage  in  other  species  of  this  genus,  the  venter  narrow,  smooth, 
concave,  as  in  Protengonoceras,  and  the  volution  also  resembhng  that  of 
that  species,  but  at  this  time  it  is  of  course  more  discoidal.  The  largest 
specimen  of  the  more  ec^mpressed  variety  reaches  a  diameter  of  134  mm. 
through  the  base  of  a  living  chamber  and  when  complete  must  have  been 
considerably  larger. 

I  have  separated  neivherryi  from  P.  })lanum  after  some  hesitation,  because 
of  the  (mtire  absence  of  the  peculiar  tuberculated  zone  of  gitadahquc  on 
the  broadened  venter  of  the  geroutic  stage,  the  more  obscure  tubercula- 
tions,  and  the  more  compressed  young.     The  second  row  of  nodes  is  more 


PLACENTICERATID^.  205 

persistent  in  the  type  specimen  than  in  other  fossils,  and  this  may  he  a 
specific  character,  although  the  condition  of  other  casts  does  not  enable 
me  to  determine  this. 

Locnlitij:  Presidio  del  Norte,  Chihuahua,  Mexico. 

Age:  Probably  same  as  guadalupce. 

Placenticeras  syrtale   (Morton). 
PL  XXVII,  figs.  1.5-17;  PI.  XXVIII,  figs.  1-6. 
Ammonites  syrtalis  Morton,  1834,  S.ynop.  Organic  Remains,  pi.  16. 

Morton's  original  specimen  is  probably  a  dwarf.  At  any  rate,  the 
shell  is  in  its  anagerontic  substage,  and  the  large  nodes  given  in  Mortoii's 
figure  belong  to  this  age.  The  diameter  is  75  mm.,  and  it  is  consequently 
smaller  than  the  specimen  of  var.  halei  below  described;  nevertheless  the 
gerontic  stage  has  begun,  as  is  shown  by  the  great  enlargement  of  the  last 
pair  of  tubercles  and  the  depression  of  the  venter,  and  there  is  no  living- 
chamber.  "When  this  was  present,  the  diameter  was  probably  about  the 
same  as  in  the  Alabama  specimen.  The  tubercles  appear  earlier  than  in 
var.  halei  and  are  larger  at  the  same  age. 

A  specimen  from  Fort  Worth,  which  shows  the  typical  characters  oi 
the  figure  given  by  Morton,  is  97  mm.  in  diameter.  Tlie  outer  volution  is 
42  mm.  from  line  of  involution  to  venter  and  the  opposite  is  31  mm.  The 
large  size  of  the  umbilicus  is  due  to  the  recession  of  the  outer  volution, 
which  is  in  its  metagerontic  substage,  and  the  shell  consequently  was  almost 
wholly  outgrown.  It  has  the  large  inner  nodes,  and  as  these  are  not  so 
numerous  as  the  next  outer  row  of  smaller  ones  there  is  a  distinct  aspect 
of  bifurcation  in  the  fold-like  costae  that  here  and  there  connect  them 
tlu-oughout  the  ephebic  and  gerontic  stages.  The  venter  has  a  narrow, 
concave  zone  bordered  by  elongated  tubercles  forming  a  crenulated  border 
on  either  side  in  the  epliebic  stage.  These  are  more  closely  set  than  in 
var.  halei  from  Alabama.  The  inner  row  of  nodes,  as  in  P.  intercalare, 
does  not  hold  to  the  line  of  the  umbilical  shoulder,  but  recedes  outwardly 
in  the  gerontic  stage,  and  this  stage  comes  in  much  earlier  than  in  intercalare 
in  all  of  these  specimens. 

The  venter  has  become  rounded  on  the  outer  quarter  of  the  last 
volution,  the  ventral  line  of  tubercles  being  lost.  The  lateral  nodes, 
however,  remain  pi'ominent,  showing  that  the  last  or  paragerontic  substage 
of  senile  development  has  not  been  reached.     The  outer  row  is  nearer  to 


206        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

the  venter  at  all  ages  than  iu  P.  intercaJarc,  and  the  volutions  are  stouter  in 
all  specimens  of  the  latter  that  approximate  iu  their  markings  to  this 
species. 

The  sutures  of  syrtale  at  the  same  age  as  that  given  by  ]\Ieek  (Invert. 
Pal.,  p.  471)  have  the  same  broad  first  lateral  saddles,  but  the  other  saddles 
are  not  so  wide  as  those  figured.  There  are,  however,  the  same  number, 
viz,  10.  They  are  all  minutely  digitate  except  the  tenth,  which  is  entire. 
The  living  chamber  is  fully  one -half  of  a  volution  in  length,  and  part  of  the 
aperture  preserved  shows  a  broad,  blunt  lateral  crest. 

This  form  is  obviously  very  similar  to  P.  intercalare  and  may  be,  if 
one  chooses,  considered  on  one  side  to  be  identical  with  P.  sancarlosense 
and  on  the  other  with  P.  intercalare.  From  the  former  it  can  be  separated 
by  the  venter,  which  is  not  so  broad  at  any  stage,  and  by  the  early 
disappearance  of  the  ventral  tubercles  in  the  gerontic  stage,  and  the  fact 
that  the  venter  becomes  rounded  only  in  extreme  age  and  is  never  flattened 
as  in  neivherriji  and  its  close  ally,  sancarlosense. 

It  can  also  be  separated  from  intercalare,  1)ut  the  characters  are  more 
dubious  It  is  certainly  so  close  that  the  differences  in  the  specimens  so 
far  known  might  be  considered  as  due  to  the  same  causes  that  dwarfed  the 
stature  of  the  shells.-  The  young,  however,  appear  to  be  more  compressed 
at  the  same  age  in  syrtale. 

Locality:  Greene  County,  Ala.;  Fort  Worth,  Tex. 

Age:  Probably  Taylor  marls  or  Austin  limestone.  Upper  Cretaceous." 

Placenticeras  syrtale  var.  halei  Hyatt. 

PL  XXVII,  ligs.  16,  17;  PI.  XXVIII,  figs.  3-6. 

This  is  found  in  the  Hale  collection  (Boston  Society  Natural  History, 
No.  8577),  and  approximates  to  polyopsis  of  Dujardin.  It  has,  however, 
much  heavier  lateral  nodes  and  costiB  in  the  gerontic  stage.  The  young 
in  the  later  neanic  stage,  judging  from  the  fragment  studied,  can  hardly  be 

«  ilr.  Stanton  has  most  obligingly  written  as  follows: 

"Locality:  'Fort  Worth,  Tex.'  It  is  not  at  all  probable  that  the  specimen  came  from  Fori 
Worth,  though  it  may  have  been  found  some  miles  east  of  there. 

"Age:  Upper  Cretaceous,  probably  Taylor  marls  or  Austin  limestone. 

"  Pldcenliccras  syrtale  var.  Iialei  Hyatt. 

"Locality:  Greene  County,  Ala. 

"Age;  This  specimen  is  probably  from  the  Eutaw  beds,  which  are  probably  very  near  the 
horizon  of  P.  yuadalupir,  in  Texas." 


PLACENTICERATID.E.  207 

sepai-ated  from  the  young  of  P.  holli,  although  the  tubercles  of  the  inner  line 
are  less  prominent  at  diameter  of  45  mm.,  the  volution  being  23  mm.  and 
greatest  transverse  diameter  11  mm.  When  the  volution  is  43  nun.  from 
lines  of  involution  to  venter  in  same  cast,  the  nodes  in  both  lateral  lines 
are  very  large  and  the  ventral  tubercles  large,  the  ventral  zone  becoming 
sinuous  on  the  cast  in  consequence  of  their  size  and  arrangement.  The 
venter  also  begins  to  show  rotundity  immediatelj^  after  this,  thus  introducing 
the  gerontic  stage;  the  lateral  zones  begin  to  lose  their  flattened  aspect, 
becoming  more  convex,  the  umbilical  shoulders  becoming  correlatively 
rounded.  Tlie  inner  lines  of  nodes  in  this  species  are  also  apt  to  be  elon- 
gated into  ridges  directed  apically,  as  in  polyopsis  Dujardin.  In  the 
parephebic  substage  the  -s^olution  from  line  of  involution  to  venter  in  cast  is 
41  mm.,  transverse  diameter  between  nodes,  which  are  not  close  to  umbilical 
lines  of  involution,  as  in  earlier  stages,  but  about  14  mm.  distant,  is  26  mm., 
and  through  the  nodes,  which  are  probably  somewhat  worn  down,  it  is 
30  mm.  In  a  more  complete  cast  of  90  mm.  in  whole  diameter,  which  has 
lost  a  trifle  on  the  venter  by  weathering,  the  same  rounding  of  the  venter 
begins  when  the  volution  reaches  about  32  mm.  in  ventro-dorsal  diameter 
from  lines  of  involution  to  venter.  The  nodes  enlarge  rapidly  in  the 
parephebic  and  gerontic  stage  of  these  two  specimens,  and  fold-like  costse 
appear  whicli  are  obscurely  bifurcated  at  the  inner  line  of  tubercles.  The 
inner  nodes  are  elongated,  and  have  heavy,  although  not  very  prominent, 
folds  on  the  umbilical  zones  which  bend  sharply  apicad.  The  ventral  zone 
gives  place  to  a  rounded  area,  as  in  the  above,  and  the  inner  nodes  are 
about  10  mm.  distant  from  lines  of  involution  instead  of  being  only  a  few 
millimeters  removed,  as  in  earher  stages.  They  are,  however,-  still  on  the 
umbilical  shoulders,  and,  therefore,  in  same  position  as  in  the  young  with 
relation  to  the  sides. 

Locality:  Greene  County?,  Alabama. 

Age:  Eutaw  beds.  Upper  Cretaceous. 

Placenticeras  intercalare  Meek. 

Pis.  XXXV-XXXVII;  PI.  XXXVIII,  fig.  1. 

Placenticeras  placenta  var.  intercalare,  Meek,  1876,  Mon.  U.  S.  Geol.  Surv.  Terr., 
Vol.  IX,  pi.  23. 

This  was  identified  by  Meek  with  placenta,  but  its  characteristics  were 
fully  given  by  him  and  its  relations  to  Ammonites  siirtalis  of  Morton  and 


208        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

the  true  placenta  correctly  defined.  In  some  parts  of  his  text  he  also 
speaks  of  this  as  " Placenticeras  intercalare,"  so  that  he  is  the  sole  authority 
for  the  combined  names  as  used  in  this  description. 

The  ventral  lobe  as  figured  by  Meek  is  very  distinct  from  that  of  P. 
ivhitfieldl,  as  are  also  the  entire  sutures.  This  lobe  is  narrower,  the 
branches  are  of  the  syrtale  type,  the  siphonal  saddle  is  more  elevated,  nar- 
rower, and  is  subdivided  by  a  median  marginal  lobe  with  a  minute  bifid 
saddle;  but  these  distinctions,  except  in  a  general  sense,  do  not  hold,  since 
there  are  the  same  types  of  siphonal  saddles  in  whitfieldi.  The  drawings 
by  Meek,  when  compared  with  the  originals,  are  accurate.  The  specimen 
on  plate  23  is  in  the  ephebic  stage.  The  sutures  overlap  as  much  as  in 
whitfieldi.  A  specimen  having  external  shell  in  part  preserved,  from  near 
Black  Hills,  South  Dakota  (purchased  from  Professor  Ward),  is  208  mm.  in 
diameter.  The  last  part  of  outer  volution  from  lines  of  involution  to  venter 
is  112  mm.,  the  first  of  the  same  being  50  mm.  The  greatest  transverse 
diameter  of  the  volution  when  it  is  95  mm.  is  44  mm.,  and  when  50  mm.  it 
is  29  mm.  The  volution  is  somewhat  stouter  than  in  ivhHfieldi  and  the 
involution  somewhat  less.  The  venter  is  a  little  broader  and  is  bordered 
by  two  rows  of  tubercles  of  good  size.  These  tubercles  quite  suddenly 
show  decrease  in  size,  and  become  much  nearer  at  the  same  time  on  the 
last  of  third  and  on  fourth  quarter  of  this  volution.  They  are  present  on 
both  cast  and  shell.  On  the  last  part  of  outer  volution  they  are  almost 
obsolescent.  On  the  fiirst  part  of  the  living  chamber  they  are  oj^posite, 
then  become  again  alternate,  and  as  they  decrease  in  size  are  again  opposite. 
The  ridges  on  the  venter  are  slight,  except  in  one  short  space,  where 
they  first  become  opposite.  The  shell  has  numerous  bands  of  growth. 
The  chevrons  are  particularly  prominent  on  last  part  of  this  volution  and 
run  into  and  form  several  longitudinal  ridges  on  the  outer  half  of  lateral 
zone,  while  the  costse.  are  represented  only  by  very  broad,  hardly 
perceptible,  folds.  The  tubercles  of  the  middle  line  are  of  good  size  and 
become  obsolete  on  the  last  quarter,  changing  at  the  same  time  with 
ventral  rows  of  tubercles.  Large  tubercles  are  present  on  the  umbilical 
shoulders,  which  sensibly  decrease  at  the  same  titne  and  also  recede 
gradually  from  the  shoulders  outwardly.  These  nodes  are  elongated, 
forming  parts  of  the  costa'  tliat  are  more  perceptible  in  their  neighlior- 
hood.     The  outlines  of  the  ventral  zone  are  not  sinuous  between  tuberch-s. 


PLACENTICERATID^E.  209 

There  is  a  thick,  opaque,  honi-colored  outer  layer',  an  intermediate 
crimson-red  layer,  and  an  inner  naci'eous  layer  of  the  usual  color.  These 
consist  of  a  number  of  minor  layers  as  in  other  shells  of  this  genus.  The 
sutures  have  broader  lobes  and  narrower  saddles  than  in  ivhitfieldi  and 
placenta,  and  the  outlines  of  these  are  somewhat  less  complicated  and  not 
so  overlapping.  The  ventral  lobe  has  the  same  narrow  character  and 
syrtakA^ke  branches,  with  large  siphonal  saddle,  as  in  Meek's  figure  of 
P.  intercalare,  but  the  siphonal  saddle  is  smooth  and  entire  on  the  venter, 
as  in  P.  tuhiffietdi,  and  also  has  the  same  minute  marginal  saddles  on  either 
side  of  this  entire  center.  A  fine  young  specimen  of  this  species,  from 
Sage  Creek,  South  Dakota,  No.  2104b  in  collection  of  Yale  Museum,  at 
diameter  of  80  mm.,  shows  the  beginning  of  the  large  tubercles  of  umbilical 
shoulder,  the  ventral  tubercles,  and  apparentl}'  those  of  the  middle  row  to 
be  on  the  first  quarter  of  its  outer  volution.  This  shell  must  have  been 
smooth  and  similar  to  P.  placenta,  perhaps,  even  in  tlie  sutures,  when  tlie 
diameter  from  line  of  involution  to  venter  was  about  15  mm.  At  later 
stages  the  sutures  are  distinct.  Another  specimen,  same  locality  and 
collection,  at  diameter  of  132  mm.,  shows  three  rows  of  tubercles  distinctly 
visible  on  botli  cast  and  shell.  No  2104a.  The  median  lateral  lines  of 
tubercles  disappear  on  the  last  quarter  of  the  outer  volution  in  this 
specimen,  but  the  ventral  inner  rows  persist.  As  long  as  the  median  rows 
of  tubercles  exist  the  .shell  has  a  transverse  outline  distinct  from  that  of 
whitfieldi  at  any  stage,  but  when  these  disappear  it  is  difficult  to  separate 
this  specimen  from  H-hitJieldi.  I  have  not  yet  seen  a  specimen  in  which  the 
ventral  rows  of  tubercles  disappear,  l)ut  whether  they  do  or  not  it  must  be 
impracticable  in  some  specimens  to  separate  them  from  whitfieldi  xav. 
tubercidatum,  although  most  specimens  are  distinct  on  account  of  the  size 
and  persistence  of  all  of  the  tubercles. 

A  fine  specimen  from  same  collection  from  Sage  Creek,  South  Dakota, 
(No.  1863)  at  diameter  144  mm.,  has  already  passed  well  into  its  gerontic 
stage,  whereas  the  specimen  figured  by  Meek  is  not  so  far  advanced  in  ao'e. 
The  first  part  of  the  last  volution  is  considerably  compressed,  as  in  Meek's 
figure,  but  on  the  living  chamber  on  the  last  half  of  this  volution  the  whorl 
becomes  stouter.  This  chamber  is  apparently  nearer  complete  and  aliout 
one-half  of  a  volution  in  length.  All  three  lines  of  tubercles  persist  and  the 
ventral  ones  which  are  alternate  in  tlie  ephebic  stage  are  apjiroximately 

MON  XLIV — 03 14 


210        FSEUDOCERATITES  OF  THE  CRETACEOUS. 

opposite  ill  old  age  ami  are  sometimes  connected  by  a  ridge,  so  that  the 
venter  is  serrated.  The  inner  line  of  tubercles  recedes  in  this  stage,  as  in 
specimen  figured  by  Meek. 

The  sutures  have  shorter,  stouter  saddles  than  those  figured  by  Meek, 
and  are  more  like  those  of  P.  syrtak.  In  the  first  lateral  saddles  especially 
thev  are  more  deeply  cut  into  by  the  lobes  that  broaden  out  apicad,  and  the 
other  lobes  and  saddles  are  like  those  of  Intercalare,  as  figured  by  Meek. 
The  resemblances  to  syrtale  occur  more  markedly  in  old  age,  when  the 
body  of  the  first  lateral  saddles  loses  the  thread-like  tenuity  of  the  ephebic 
stage  and  becomes  thicker.  All  the  saddles  do  not  show  these  changes 
equally.  This  last  specimen  has  enabled  me  to  make  connections  with  No. 
18975  U.  S.  National  Museum,  from  the  Upper  Missouri,  which  is  a  nearer 
approach  to  syrtale.  The  inner  nodes  on  this  last  are  about  the  same,  but 
are  not  partly  buried  by  the  involution  and  make  their  appearance  some- 
what earlier  in  the  neanic  stage.  The  outer  line  of  tubercles  are  larger  and 
the  venter  is  broader.  The  sutures,  however,  and  the  proportions,  etc.,  of 
the  volutions  are  about  the  same.  Lastly  there  is  a  fragment  in  same 
collection,  locality  No.  1720,  5  miles  southeast  of  Harpers  Station,  Laramie 
Plains,  Wyo.,  that  no  one  would  think  of  separating  from  syrtale  by  the 
external  characters.  The  diameter  is  94  mm.,  and  the  specimen  has  the 
same  wide  umbilicus,  stout  volutions,  prominent  nodes,  and  sharp  ventral 
tubercles  as  that  species.  The  sutures,  however,  although  the  .specimen  is 
so  small,  are  almost  as  excessively  complicated  in  outlines  as  in  Meek's 
figure,  although  this  was  taken  from  a  much  larger  volution. 

One  specimen.  No.  9735,  U.  S.  National  ]\Iuseum,  from  Ponil  Canyon, 
New  Mexico,  has  characters  just  intermediate  between  P.  intercalare  and 
P.  placenta.  The  young  and  full  e^jhebic  stage  has  the  form  of  the  stouter 
specimens  of  intercalare  with  three  rows  of  tubercles.  The  two  outer  rows 
are,  however,  more  delicate  than  usual  in  intercalare,  especially  the  median 
lateral  ones,  wliich  are  very  small  and  widely  separated  as  in  P.  jilaceiifa. 
Unfortunately  the  last  of  the  ephebic  and  the  first  part  of  the  gerontic 
stages  are  missing,  but  the  parts  left  show  similarity  with  the  old  age  of 
P.  placenta  and  intercalare.  The  venter  does  not  broaden  out  except  very 
slightly  wliile  becoming  rounded  as  it  does  on  the  third  quarter  of  the 
outer  volution.  The  sides  lose  the  abrupt  elevated  umbilical  shoulders  and 
become  evenly  convex,  but  the  involution  continues  to  follow  the  umbilical 


PLACENTICERATID.E.  2 1 1 

line  of  tubercle.s.  The  ventral  lines  of  tubercles  persist  on  the  outer 
volution,  but  are  very  faint  and  tiually  disappear.  The  same  is  true  of  the 
other  lines  of  tubercles,  all  of  which  finally  disappear  in  the  paragerontic 
stage.  The  shells  of  this  species  do  not  apparently  have  the  gerontic 
enlargement  of  tubercles  into  heavy  blunt  nodes  which  is  common  in 
ffiiadalitjue  and  its  allies,  sancarlosense,  planum^  and  also  5^rto/e.  The  sutures 
are  like  those  of  syrtale  and  less  complicated  than  in  intercalare  at  tlie  same 
age,  but  this  appearance  is  probably  largely  due  to  the  fact  that  they  are 
less  crowded  and  do  not  overlap. 

Locality:  Black  Hills  region. 

Age:   Fort  Pierre  group,  Upper  Cretaceous. 

Placenticeras  placenta  (Dekav). 
PI.  XXXIX.  figs.  3-6:  PI.  XL.  fio-,s.  i.  ± 

Ammonites  placenta  Dekay.  lS:iS.  Ann.  New  York  Lvc.  Nat.  Hist..  Vol.  II,  pi.  5,  fig-.  :?, 

not  fig.  3. 
Placenticeras  2>ltt^ent a  Meek  (pars),  1876,  Mon.  U.  S.  Geol.  8urv.  Terr.,  Vol.  IX, 

p.  465. 
Placenticeras  placenta  Whitfield  (pars).  1892.  Mon.  U.  S.  Geol.  Survey,  Vol.  XVIII, 

pis.  40,  41. 

This  species  is  represented  in  the  Museum  of  ( 'omparative  Zoology 
by  a  large  fragment  from  New  Jersey  101  mm.  in  diameter  from  line  of 
involution  to  venter  at  base  of  living  chamber,  and  this  last  is  about 
one-half  of  a  volution  in  length.  It  is  a  cast  and  smooth  on  the  sides,  with 
the  exception  of  a  line  of  fold-like  tubercles  on  the  depressed  umbiHcal 
shoulders.  The  ventral  zone,  even  at  this  stage,  obviously  fully  gerontic, 
is  flat  and  7.5  mm.  broad  as  estimated. 

The  last  sutures  have  not  so  highly  complicated  outlines  as  whitfiehU, 
but  the  lobes  are  long  and  narrow,  the  first  and  second  laterals  highly 
inclined  apically.  The  fourth  lateral  is  about  two-thirds  as  long  or  only 
slightly  shorter  than  the  third  lateral  lobe.  The  saddles  are  not  so  deeply 
divided  as  in  tvkitjieldi  and  broader  and  more  solid.  The  last  two  sutures 
are  approximated,  but  the  third,  although  partly  preserved,  is  at  the  usual 
distance  and  shows  that  this  is  not  the  same  as  the  western  form  described 
by  Meek  as  placenta.  The  sutures  of  this  large  specimen  of  P.  placenta 
have  exactly  the  outlines  given  by  Whitfield  in  his  figure,  and  a  similar, 


212        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

altliougli  perha23S  older,  siphonal  saddle  has  numerous  denticles  or  marginal 
saddles.  The  median  marginal  lobe  was  not  quite  so  plain  as  in  Whitfield's 
figure,  but  this  might  have  been  owing  to  age  or  variation  in  sutures  or  the 
condition  of  the  cast.  Meek,  as  well  as  Whitfield,  included  under  placenta 
several  species  which  are  separated  in  these  descriptions,  but  Whitfield 
recognized- and  described  the  differences  between  the  western  and  the  New 
Jersey  specimens  and  considered  them  as  probably  distinct.  I  have 
consefpiently  named  the  western  species  whitfieldi  in  recognition  of  this 
fact. 

The  specimen  described  above  enables  me  to  add  the  following:  The 
venter  is  not  rounded  on  the  smaller  end  of  this  cast,  but  flat,  having  the 
same  form  as  whitfieldi,  but  broader  than  in  that  species;  subsequently, 
although  not  well  preserved,  this  part  appears  to  become  rounded.  This 
specimen  shows  that  in  extreme  age  the  volution  is  shorter  and  has  more 
gibbous  sides  than  in  whitfieldi  and  shorter  ventro-dorsal  diameters.  The 
decrease  in  involution  due  to  senility  is  also  more  marked,  and  takes  place 
at  a  smaller  size.  This  species  stands  between  si/rtale  and  whitfieldi  in 
this  respect  and  in  its  sutures  and  other  characters. 

There  are  several  fragments  in  the  Hale  collection  of  the  Boston 
Society  of  Natural  History,  supposed  to  be  from  Greene  County,  Alabama, 
which  have  saddles  with  more  solid  bodies  or  basal  parts,  as  in  true 
placenta  These  indicate  a  species  of  larger  size  than  the  associated  species 
of  P.  si/rtale,  having  volutions  with  smooth  flat  sides  and  smooth  venter, 
as  in  placenta.  The  sutures  agree  very  closely  with  those  given  by 
Morton  for  P.  placenta  from  the  cut  of  the  Delaware  and  Chesapeake  Canal, 
and  one  specimen  shows  a  rounded  venter.  The  examination  of  the  fine 
suite  of  original  types  and  specimens  in  the  Museum  of  the  Academy  of 
Sciences  of  Philadelphia  gave  the  following  results:  The  septum  of  this 
species  is  much  flatter,  ha\T[ng  only  a  very  slight  double  curvatui-e  ni  place 
of  the  very  marked  double  curvature  of  whitfieldi,  and  this  is  less  apparent 
on  the  suture  line  than  on  the  surface  of  the  septum.  On  a  volution  63 
mm.  from  line  of  involution  to  venter,  transverse  diameter  is  22  mm.  and 
there  are  three  lines  of  tubercles.  The  lateral  row  is  two-thirds  of  the 
breadth  of  the  sides,  nearer  the  venter  than  the  dorsum,  and  very  small 
and  widely  separated,  but  still  quite  distinct.  The  tubercles  on  the  venter 
of  placenta  are  large  and  elongated  like  those  of  holli  and  much  coarser  and 


PLACENTICERAT1D.E.  213 

less  numerous  tlian  in  some  specimens  of  whitfiekU.  These  disa^jpear  in 
the  ephebic  stage,  together  with  the  lateral  line  of  tubercles,  and  in  some 
specimens  the  latter  may  be  entirely  absent  as  in  young  specimens  figured 
by  Whitfield.  The  large  originals  of  Morton's  figure  and  of  Whitfield's 
show  these  figures  to  be  approximately  correct.  The  venter  is  in  all  stages 
broader  than  in  true  ivhitjieldi,  but  remains  flat  only  through  a  small  j^art 
of  the  gerontic  stage.  In  two  specimens,  365  mm.  and  425  mm.  in  diameter, 
one  Morton's  type,  trom  cut  of  Delaware  and  Chesapeake  Canal,  the  living 
chamber  was  practically  complete  and  about  one-half  of  a  volution  in 
length.  The  rounding  of  the  venter  begins  in  these  on  the  still  separate 
part  of  the  second  quarter  of  the  outer  volution.  Near  the  aperture  the 
venter  is  completely  rounded  and  the  decrease  in  the  ventro-dorsal  diameters 
between  the  lines  of  involution  more  marked  than  in  whlt/ieldi,  and  the 
umbilici  are  consequently  larger.  The  sutures  vary  from  having  very  solid- 
looking  saddles  as  in  Whitfield's  figui-e  to  those  with  the  first  to  third 
saddles  almost  indistingviishable  from  those  of  some  varieties  of  tvhitjieldi. 
Upon  the  whole,  however,  it  is  safe  to  say  that  while  the  saddles  of  placenta 
may  be  as  deeply  undercut  and  the  necks  as  thin  as  in  whiffieldi,  the  basal 
parts  are,  perhaps,  always  less  completely  cut  up  by  the  marginals.  These 
and  the  auxiliary  saddles  have,  however,  as  a  rule,  a  bifid  aspect  with  a 
large  median  marginal  deeply  dividing  them,  and  this  seems  to  be  a  distinc- 
tion of  more  importance,  especially  in  the  aspect  of  the  auxiliaries.  The 
proportions  of  the  diameters  are  also  quite  different.  In  the  ephebic  stage 
the  transverse  diameter  may  be  more  or  less  than  one-third  of  the  diameter 
from  line  of  involution  to  venter  and  in  old  age  it  may  be  more  or  less 
than  one-half  of  this  same  diameter.  A  yomig  specimen  of  diameter  of 
about  60  to  65  mm.  is  in  collection  of  the  Academy  of  Sciences  of  Phila- 
delphia. In  the  neanic  stage  this  cast  had  highly  compressed  smooth 
volutions  as  in  ivhiifiehU,  but  the  umbilicus  is  larger,  the  involution  being- 
somewhat  less,  apparently.  The  three  lines  of  tubercles  begin  on  the  first 
part  of  the  outer  volution  or  just  before,  when  the  shell  is  about  45  mm.  in 
diameter.  At  this  stage  the  lobes  and  saddles  are  distinctly  placenticeran. 
The  saddles  are  all  bifid,  but  the  entire  outlines  have  given  place  to  com- 
pletely denticulated  outhnes  over  both  lobes  and  saddles,  even  on  the 
innermost  auxiliaries  in  the  older  parts  of  this  cast.  The  sutures  at  this 
age  are  very  similar  to  those  of  syrtale  and  guadalupce. 


214        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Until  a  late  age  this  shell  is  separable  from  stantoni  or  psendoplacenta 
by  the  preseuce  of  the  minute  median  lateral  line  of  tubercles.  Tlie  larger 
size  and  wider  separation  of  the  ventral  tubercles  separate  the  younger 
stao-es,  in  which  the  venter  is  often  very  narrow  and  the  sutures  similar  to 
those  of  tvJdtfieldi,  from  var.  tuberculatum  of  that  species.  The  sutures, 
however,  as  a  rule,  liave  less  complex  outlines  and  more  solid-bodied  saddles 
and  less  concave  septa,  as  stated  above. 

LocalHy:  New  Jersey,  Alabama. 

Aye:  Matawan  formation  (clay  marls),  Upper  Cretaceous. 

Placenticeras  stantoni  n.  sp.  Hyatt. 

Placenticeras  placenta  Stanton  (pars.),  ISiM.  Bull.  U.  S.  C°ol.  Survey  No.  Kni,  pi.  39, 
figs.  2,  3,  not  fig  1. 

Locality:  Upper  Kanab  Valley,  Utah. 
Age:  Colorado  epoch.  Upper  Cretaceous. 

Placenticeras  stantoni  variety  bolli  Hyatt. 
PI.  XL,  figs.  3-7;  PI.  XLI:  PI.  XLIl:  PI.  XLIII.  figs.  1.  ± 

Placenticeras  intercalare  Meek  (par^s.),  1876,  Mon.  U.  S.  Geol.  Surv.  Terr.,  Vol.  IX, 
p.  471. 

This  species  is  very  like  P.  placenta  and  irhiffieldi,  but  has  much  stouter 
volutions  with  broader  venters  at  the  same  age  and  is  intermediate  in 
character  between  intercalare  and  whitfieldi.  The  costse  are  of  tlie  syrtale 
type,  but  are  merely  obscure  folds  on  these  casts.  The  tubercles  are  sparse 
and  on  the  umbilical  shoulders  as  in  placenta.  The  costa^  are  occasionally 
bifid  on  the  outer  part  of  the  side  with  single  ones  between  them.  Tlie 
elonofated  ventral  tubercles  are  alternate  and  each  one  has  its  costation. 
The  sutures  have  much  shorter  lobes  and  stouter,  shorter  saddles  than  in 
placenta. 

The  young  in  the  nepionic  stage  have  a  smooth  volution  with  rounded 
venter.  In  the  neanic  stage  this  changes  through  the  elevation  of  the  venter. 
The  ventral  zone  is  at  first  quite  broad  comparatively  and  perfectly  flat  in 
the  neanic  stage.  In  the  ephebic  stage  it  becomes  much  naiTower  and  con- 
cave and  probably  then  acquires  its  tubercles.  The  tubercles  on  the 
umbilical  shoulders  do  not  appear  until  this  stage  begins. 


PLACENT7CERATID.E.  215 

The  lateral  augles  of  the  single  costai,  and  still  more  the  junctions  of  the 
dichotomous  costse,  when  these  occur,  tend  to  rise  up  more  ^prominently 
than  the  rest  of  the  costatiou  as  in  other  forms,  but  they  do  not  in  the 
specimens  examined,  as  in  syrtale  and  interculare,  become  tuberculose.  The 
specimens  from  which  these  descriptions  were  taken  are  in  the  Museum  of 
Comparative  Zoology. 

This  species  is  distinguished  from  P.  placenta  by  the  shorter  and  stouter 
lobes  and  saddles  and  the  better  separation  of  the  sutures  at  all  stages 
except,  perhaps,  the  youngest.  It  stands  apparently  nearer  to  P.  syrtale 
in  its  sutures  than  to  intercalare,  but  this  is  due  to  the  fact  that  in  intercalare 
the  sutures  vary  from  those  like  syrtale  to  as  complicated  as  iu  Meek's 
figures,  and  if  the  comparisons  are  made  with  the  former,  it  is  seen  that  the 
external  characters  and  sutures  place  it  between  intercalare  and  ivUtfieldi,  on 
account  of  the  suppression  iu  both  of  the  lateral  line  of  tubercles.  A  speci- 
men from  Dallas  County,  Tex.,  has  similar  markings  and  sutures  so  far  as 
seen  on  the  young  volutions,  and  is  probably  the  gerontic  stage  of  this 
species.  It  is  an  incomplete  living  chamber  al)out  one-half  of  a  volution  in 
length,  witli  the  inner  volutions  attached  l)ut  l)adly  crushed.  The  latter 
shows  the  large  inner  row  of  nodes  and  the  sutures  in  part,  and  these  last 
agi-ee  closely  with  those  of  the  specimen  described  above. 

The  volution  from  line  of  involution  to  venter  at  base  of  living  chamber 
is  75  mm.  in  diameter,  transverse  diameter  about  40  mm.,  and  at  one-fourth 
of  a  volution  distant  from  this  the  diameter  is  91  mm.  The  venter  is  broad, 
and  the  ventral  zone  convex  on  the  cast  at  the  two  last  septa.  The 
tubercles  are  almost  obsolete  and  the  cost£e  completely  gone,  the  cast 
being  smooth  with  the  exception  of  one  obscure  broad  longitudinal  ridge 
on  the  centrau  surface  of  the  lateral  z(jne.  The  remnants  of  tubercles 
are  shown  in  obscure  and  very  slight  folds  with  a  decided  apical  trend. 
This  desci-iption  shows  that  the  gerontic  stage  is  quite  distinct  from  that  of 
placenta  or  ivhitfielcli. 

The  basal  suture  is  very  complex  in  its  outlines,  but  has  the  short 
saddles  and  lobes  of  this  species.  The  next  younger  septum  is,  however, 
closely  approximated  to  the  last.  The  first  and  second  lateral  lobes  are 
very  narrow  and  the  saddles  approximate.  The  lateral  lobe  is  also  narrow. 
The  remaining  lobes  and  saddles  are  more  like  those  of  the  younger  stao-es, 
but  also  have  narrower  lobes  and  broader  saddles.     These  suture's  are  quite 


216        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

distinct  from  tliose  of  other  species  and  come  nearer  to  those  of  the  old 
whorl  of  P.  placenta  from  New  Jersey  than  any  other  fonn.  They  are, 
however,  smaller,  and  the  apical  trend  of  the  outer  lobes  is  less,  the  third 
lateral  being'  shorter,  and  the  remaining  lobes  more  abruptly  separated 
through  their  extreme  shortening  up  as  compared  with  the  third  lateral. 

Having  received  through  Professor  Mai'tin  the  specimen  described  by 
Meek  from  Tarrant  County,  Tex.,"  as  belonging  to  P.  intercalare,  I  am  able 
to  state  that  it  is  a  good  cast  of  this  species.  The  diameter  is  90  mm. 
The  living  chamber  is  incomplete  but  nearly  half  of  a  volution  in  length. 
The  median  lateral  line  of  tubercles  is  absent,  the  inner  line  of  small 
tubercles  recedes  from  the  umbilical  shoulder,  and  the  ventral  tubercles 
are  rather  coarse  and  large,  and  the  venter  broad  as  in  typical  holli.  The 
sutures  have  the  solid  short  saddles  and  short  lobes  of  this  form.  The 
paraphebic  substage  is  reached  near  the  aperture. 

LocaUUj:  Elm  Fork  and  West  Fork,  Dallas  County  and  Tarrant 
County,  Tex. 

Aye:   "Probably  Eagle  Ford  shales"  (Stanton) 

Placenticeras  pseudoplacenta  Hyatt. 

PI.  XLIII,  figs.  3-11;  PI.  XLIV. 

Placenticeras  placenta  (?)  Stanton  (pars),  ISOi.  Bull.  U.  S.  Geol.  Surve}'  No.  106, 
pi.  39,  fig.  1  (not  figs.  2,  3.) 

The  sutiu-es  are  peculiar  and  unlike  those  of  any  of  the  forms  of  true 
P.  placenta  or  ivliitfielcli.  This  fact  was  noticed  by  Stanton,  who  considered 
the  Colorado  species  to  be  different  from  true  placenta.  In  confirmation  of 
these  remarks  I  can  add  the  following:  A  large  fragment,  U.  S.  National 
Museum,  locality  Upper  Kanab,  Utah,  No.  22344,  diameter  from  line  of 
involution  to  venter  88  mm.,  greatest  transverse  about  35  mm.,  shows  a 
wider  venter  6  mm.  and  flatter  than  in  irhitfielcli  at  same  age.  The  side 
which  is  unaffected  by  pressure  is  nut  so  evenly  convex  as  in  that  species, 
the  outer  part  being  very  slightly  concave,  the  centran  part  slightly 
gibbous.  The  sutures  exhibit  more  complicated  outlines  than  in  the 
younger  stage  figured  by  Stanton,  but  they  have  similar  ragged  outlines 
and  very  broad  lobes  and  are  obviously  the  same.  A  specimen  with 
diameter  of  35  mm.  has  on  the  last  volution  sutm-es  with  same  rugged 


«Mon.  U.  S.  Geol.  Survey  Terr.,  Vol.  IX,  j).  471. 


PLACENTICERATIDiE.  2 1 7 

aspect  but  very  much  simpler  in  outline  than  those  of  P.  whitfieMi  or  even 
those  of  true  placenta  at  the  sr«me  age.  The  perfect  venter  at  this  stage  is 
concave  and  it  continues  smooth  and  concave  in  this  species  until  the  shell 
is  much  larger,  but  then  becomes  flattened  and  apparently  exactly  similar 
to  that  of  true  P.  placenta,  but  is  broader  at  the  same  age  and  flatter  than 
in  P.  whitfiekU.  The  sutures  are  more  like  those  oi  P. placenta  than  those  of 
P.  whitfieldi.  The  casts  do  not  show  the  shell  except  in  the  young  stage 
and  this  has  obscure  sigmoidal  bands  of  growth  like  those  in  whitfieldi  but 
no  costfe  on  the  shell  and  none  on  the  casts  as  is  usual  in  that  species. 
The  youngest  stage  is  more  involute  than  in  P.  placenta  and  is  like  some 
specimens  of  P.  whitfieldi  in  this  respect. 

Stanton's  figure  of  the  suture  was  taken  from  the  ephebic  volution  of 
a  specimen  of  the  diameter  of  173  mm  The  volutions  were  perfectly 
smooth  on  this  cast,  with  a  flat,  broad  venter,  and  at  the  diameter  given  on 
the  third  quarter  of  the  outer  volution  the  gerontic  stage  had  begun  and 
the  last  part  of  the  volution  was  helmet-shaped  in  section  with  a  rounded 
venter.  This  shows  a  paragerontic  stage  earlier  than  is  usual  in  ptlacenta  or 
in  irhiffieldi. 

The  specimen  alluded  to  by  Stanton,  from  Ellis  County,  Tex.,  Eagle 
Ford  shales  or  Fort  Benton  Group,  is  a  cast  1?1  mm.  in  diameter,  with 
form  almost  as  much  compressed,  and  with  thin  venter,  as  in  whitfieldi,  but 
the  sutures  are  more  like  those  of  stantoni.  They  are,  however,  more 
deeply  cut,  being  older  than  those  figured  and  more  like  those  of  whitfieldi. 

In  fact,  I  do  not  see  here  nor  elsewhei'e  any  possibility  of  drawing- 
sharp  lines,  except  between  the  genera;  the  species  all  run  into  one  another. 

Locality:  Upper  Kanab,  Utah;  Huerfano  Park,  Colorado. 

Age:  Colorado  Epoch,  Upper  Cretaceous. 

Placenticeras  pseudoplacenta  variety  occidentale  Hyatt. 

PI.  XLV,  figs.  1,  2. 

The  saddles  and  lobes  have  the  elongated  forms  of  those  of  P.  whit- 
fieldi, but  are  more  solid;  the  ventral  lobe  has  the  same  elongated  arms,  and 
the  ventral  saddle  is  also  similar,  but  the  lobes  and  saddles  are  simpler  and 
more  like  syrtale  until  a  later  stage  than  in  P.  whitfieldi.  The  shells  have 
a  row  of  tubercles  on  the  umbilical  shoulders  and  fine  tubercles  on  the 
venter.     The  principal  distincti(ju  is,  however,  the  breadth  of  the  venter 


218        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

and  itfi  flatuess  in  the  ephebic  stage,  which  is  simihir  to  stantoni  and 
jjlacenta.  There  are,  howe^•er,  some  specimens  witli  smooth  A-enter,  as  in 
tvhifjieldi.  A  specimen  in  the  collection  of  Colmiibia  University,  New  York 
Citv,  No.  10622G,  from  Upper  Missonri  River,  has  a  diameter,  ])artlv 
estimated,  of  150  mm.  Tlie  last  volution,  with  living-  chamber,  is  76  mm., 
partly  e.stimated;  the  umbilicus  is  22  mm.,  and  opposite  the  same  volution, 
from  line  of  involution  to  venter,  is  52  mm.  The  vofutiou  is  not  so  flattened 
or  compressed,  having  slight  ventral  tubercles  and  slight!}-  more  gibljous 
sides  than  in  irhiffieldi,  and  volutions  not  so  deeply  involute,  as  is  shown  by 
the  breadth  of  the  umbilicus.  The  line  of  involution  is  outside  the  line  ot 
internal  tubercles,  and  this  more  open  a.spect  of  the  umbilicus  and  tlie  solid 
aspect  of  the  saddles  and  forms  of  the  lobes  agree  more  closely  with  the 
smaller  form  of  phcenta  figured  l)y  Whitfield  and  are  quite  distinct  from 
true  whitfieldi  of  the  same  size. 

The  living  chamber  is  incomplete,  but  occupies  about  half  a  volution 
in  length,  and  the  aperture  follows  the  bands  of  growth.  The  siphonal 
saddle  has  several  minute  denticulations  even  at  this  early  age  Sutures  at 
diameter  of  26  mm.,  from  line  of  involution  to  venter,  showed  distinctly  the 
syrtale  type  of  outline  which  occurs  in  whitfieldi,  only  at  a  much  earlier 
stage,  short,  broad  saddles  and  con-esponding  lobes,  with  well-separated 
outlines  and  no  appearance  of  bands  free  of  sutures  on  either  side  of  venter. 

No.  8238,  U.  S.  National  Museum,  from  Cow  Island,  Upper  Missouri 
River,  Fort  Pierre  or  Fox  Hills  Group,  is  a  ver}'  interesting  fragment  of 
this  form.  It  is  a  good-sized  fragment,  showing  the  inner  and  outer  volu- 
tions, with  broad  ventei's  and  proportions  stouter  than  in  typical  psetido- 
placenta  or  whitfieldi.  The  tubercles  on  the  venter  are  not  large,  but  quite 
plain.  Thev  disappear  on  the  last  of  the  outer  volution,  while  the  inner 
line  pei'sist,  and  there  is  no  median  line.  There  is  on  the  last  part  of  the 
outer  volution,  in  the  beginning  of  the  gerontic  stage,  a  distinct  elevation 
along  the  line  usually  occupied  by  the  median  lateral  tubercles,  which  I 
have  never  seen  in  tvhitfieldi,  and  which  usually  occurs  only  in  syrtale, 
intercalare,  and  the  more  heavily  tuberculated  forms.  This  is  also  apparent 
in  the  full  ephebic  stage,  but  is  less  marked.  The  sutiu'es  are  very  similar 
and,  in  fact,  not  distinguishable  from  those  of  whitfieldi  in  some  varieties. 
I  have,  in  consequence,  placed  this  shell  under  name  of  pseudoplacenta, 
although  in  general  aspect  it  really  seems  to  agree  better  with  staiitoiii. 


PLACENTICERATID.E.  219 

One  specimen,  a  fragment  given  b}'  Dr.  R.  T.  Jackson,  said  to  have 
come  from  Bad  Lands,  near  Black  Hills,  South  Dakota,  is  73  nnn.  from  the 
lines  of  involution  to  the  venter  at  small  end,  and  88  mm.  at  a  distance  of 
110  mm.,  measured  along  the  eentran  axis  of  the  side,  or  somewhat  more 
than  one-fourth  of  a  volution  farther  on,  the  whole  length  being  160  nun. 
This  fragment  is  a  living  chamber,  the  last  septum  and  the  aperture  being 
partly  preserved.  A  restoration  of  the  whole  coil  shows  the  diameter  of  the 
entire  specimen  to  have  been  about  1 74  mm.  The  obsolescing  costaj,  sparse 
and  small  tubercles  on  umbilical  shoulders,  and  small,  more  closely  set 
tubercles  on  the  edges  of  the  venter,  show  that  this  is  probably  the 
parephebic  stage  of  this  species. 

The  venter  has  become  rounded,  or  rather  the  previously  concave  zone 
has  become  convex,  but  the  ventral  tubercles,  although  faint,  are  clearly 
discernible  at  the  oldest  end  of  this  fragment. 

Thus  the  gerontic  stage  must  have  begun  in  this  species  at  a  size  when 
the  ephebic  stage  was  not  yet  completed  in  P.  whitfieldi  or  placenta.  The 
saddles  of  the  last  septum  show  much  less  complex  outlines  than  in  ivhltfieldi. 
The  third  lateral  lobe  was  not  entirely  preserved,  but  it  was  obviously  not 
so  long.  The  outlines  resemble  approximately  those  of  holli.  Dissecting- 
out  a  part  of  the  ephebic  volution  contained  in  the  zone  of  involution,  the 
shell  and  the  sutures  also  were  found  perfectly  preserved.  The  probable 
diameter  of  the  volution  at  this  age  from  line  of  involution  across  side  to 
venter  was  about  35  mm.,  and  the  whole  diameter  of  coil  perhaps  75  mm. 
The  shell  at  the  younger  end  of  this  fragment,  which  was  about  one-fourth 
of  a  volution,  showed  a  decidedly  concave  venter;  the  cast  was  also  slightly 
concave.  At  the  other  end,  while  the  shell  was  still  concave,  the  cast  was 
flat  on  the  venter.  The  tubercles  on  the  younger  end  were  well  defined, 
but  mere  fine  crenulations,  as  in  P.  placenta  and  whitfieldi.  Thev  were  barely 
perceptible  on  the  cast  at  this  end  of  the  fragment,  and  not  visible  at  all  on 
the  cast  at  the  other  end,  although,  as  stated  above,  present  on  the  cast  of 
the  gerontic  living  chamber.  The  sutures  showed  somewhat  more  solid 
branches  on  the  saddles  than  in  ivJiitfiekU,  and  ventral  lobes  and  siphonal 
saddles  like  those  of  P.  interccdare.  Previous  to  cracking  out  this  fragment 
the  specimen  was  classified  with  variety  holli.  The  chevron  markings  on  the 
nacreous  layer  were  beautifully  displayed  and  very  instructive.  At  the 
younger  end  they  had  the  normal  orad  direction  for  about  an  inch,  then 


220        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

some  accident  had  happened  fracturing  the  edges  of  the  aperture  on  both 
sides  and  causing  a  slight  sinuous  constriction  on  both  sides  when  growth 
was  resumed.  Beyond  this  the  direction  of  the  chevron  hues  was  reversed 
on  the  right  side  in  a  median  depression  and  on  the  left  along  a  slight 
corresponding  elevation. 

One  fragment  from  Elm  Fork,  Dallas  County,  Tex.,  in  the  Museum  of 
Comparative  Zoology,  not  quite  one-half  of  a  volution  in  length  and 
measuring  230  mm.  in  diameter,  has  these  characters,  but  the  umbilicus 
does  not  appear  to  be  quite  so  large  in  proportion.  The  aspect  of  the 
saddles  enables  one  to  separate  these  from  var.  tuberculatum  of  P.  whitfieldi, 
but  it  is  probable  that  these  two  are  connected.  As  I  have  repeatedly 
stated  elsewhere,  I  consider  this  varietal  connection  no  argument  for  uniting 
these  obviously  distinct  species.  This  specimen  has  large  marginal  saddles 
on  the  siphonal  saddle,  and  a  distinct  marginal  median  lobe,  which  becomes 
slightly  trifid  in  later  stages.  On  the  left  side  of  this  are  entire  slightly 
phvlliform  saddles,  and  on  the  right  a  bifid  marginal.  These  become 
subdivided  later.  The  ventral  lobe  has  the  long  arms  of  the  whUfieldi  type 
which  are  not  similar  to  those  of  the  same  lobes  in  the  syrtnle  type. 

I  propose,  in  following  the  indications  of  these  observations,  to  confine 
this  name  to  those  forms  of  this  genus  having  broad  venters  and  more 
immature  sutures  than  in  whiffieldi  at  all  stages  of  growth.  The  edges  of 
the  venter  may  be  either  finely  tuberculated  or  smooth.  The  sides  may 
be  smooth  or  with  a  median  line  of  very  obscure  elevations.  The  inner 
line  of  tubercles  is  developed,  but  does  not  appear  at  an  early  stage. 

Locality:  Elm  Fork,  Dallas  County,  Tex.;  Upper  Missoui-i,  Bad  Lauds, 
South  Dakota. 

Acje.:"  Probably  Fort  Pierre  group.  Upper  Cretaceous. 

«The  following  note  has  been  kindly  added  by  Mr.  Stanton: 

" Placenticeras  pseudoplacenta  var.  oceidenkde  Hyatt. 

"Locality:  Upper  Missouri.     Bad  Lands,  South  Dakota. 

"Age:  Fort  Pierre  group,  Upper  Cretaceous. 

"The  specimen  from  the  Bad  Lands  is  certainly  from  the  Fort  Pierre,  and  the  one  from  the 
Upper  Missouri  probably  is  also. 

"The  specimen  labeled  'P.  pseudoplacenta  var.  occidentak'  and  also  'var.  intermedium'  from  Elm 
Fork  and  West  Fork  (Horton's  mill),  Dallas  County,  Tex.,  if  the  locality  can  be  trusted,  is  probably 
from  the  Eagle  Ford  shales,  which  are  about  equivalent  to  the  Fort  Benton."  (The  locality  referred 
to  is  trustworthy. — A.  H.) 


PLACENTICERATID^E.  221 

Placenticeras  whitfieldi  n.  sp.  Hyatt. 

PI.  XLV.  tigs.  3-K3;  PI.  XLVl;  PI.  XLVII,  figs.  1-4. 

Placenticeras  'placenta  Meek  (pars),  1S70,  Mon.  U.  S.  Geol.  Surv.  Terr.,  Vol.  IX, 
pi.  24,  %.  2. 

This  species  can  be  distinguished  from  true  P.  placenta  of  New  Jersey 
and  the  supposed  western  members  of  the  same  species  by  the  following 
characters.  The  highly  compressed  volutions  are  more  involute  and  tlie 
venter  is  narrower  throughout  life  and  less  completely  rounded  in  old  age, 
and  this  change  comes  in  only  at  a  much  larger  size  than  in  the  shells  of 
P.  placenta.  Owing  also  to  the  absence  of  the  median  lateral  line  of  tuber- 
cles the  volution  has  flatter  sides.  All  tubercles  are  wanting  in  typical 
forms  at  all  stages,  but  very  fine  tubercles  are  present  on  either  border  of 
the  venter  and  larger  ones  on  the  umbilical  shoulders  in  some  shells. 
Sometimes  minute  tubercles  are  present  on  the  median  part  of  the  lateral 
aspect,  but  these  occur  only  in  the  neanic  stage,  disappearing  with'  the 
ventral  tubercles  in  the  ephebic  stage.  The  sutures  are  more  complicated 
in  the  young  and  are  more  overlapping  than  in  placenta.  The  saddles  are 
almost  linear  because  of  the  excessive  development  of  the  lobes,  which  are 
very  long  and  narrow.  These  differences  hold  with  the  materials  so  far 
examined.  It  must  be  remembered,  however,  that  as  yet  no  examination 
of  a  large  number  of  specimens  of  both  species  from  the  same  locality  has 
been  made,  and  it  is  likely  that  there  are  intermediate  shells.  Certainly  no 
one  can  distinguish  these  species  unless  familiar  with  both  forms  or  having 
both  for  comparison.  The  same  may  be  said  of  P.  intercalare,  between 
which  and  this  species  there  are  intermediate  shells  in  P.  whit/ieldi  var. 
tuberculatum. 

I  made  special  examination  of  the  ventral  lobes  of  whitfieldi  in  all 
available  specimens.  All  had  the  peculiar  very  broad  ventral  lobes  with 
long  nari-ow  branches  on  the  lateral  aspects  except  in  rare  cases  in  which 
Si/rte/e-like  or  blunter  arms  were  present.  One  specimen  had  the  lono- 
narrow  arm  on  the  right  side  and  a  blunt  syrtcde-Wka  arm  on  the  left  side. 
As  a  rule  the  ventral  Jobe  is  symmetrical,  but  the  siphonal  saddle  is  often 
unequall}^  developed  or  out  of  place.  This  saddle  is  often  entire  and  flat,  so 
that  one  is  apt  to  regard  this  as  the  normal  form,  but  variations  are  so 
frequent  that  only  large  numbers  of  specimens  could  determine  the  facts. 


222        PSEUDOCEKA'PITES  OF  THE  CRETACEOUS. 

This  saddle  may  have  a  simple  median  marginal  saddle  or  be  trifid  with 
three  saddles,  equal  or  unequal  in  size;  or  it  may  l)e  bifid,  with  Ijotli  mar- 
ginals again  subdivided,  or  of  any  sliape  between  these  and  such  irregular 
sinuous  outlines  that  it  is  diflficult  to  describe  it.  It  is  almost  invarialily 
sunken  between  two  marginal  saddles,  one  on  either  side,  but  occasionally 
even  these  blend  with  the  central  part  of  the  siphonal  saddle. 

A  specimen  from  Cheyenne  River,  South  Dakota,  in  the  collection  of 
Columbia  University,  New  York  City,  reaches  327  mm.  in  diameter  and  has 
the  basal  part  of  a  living  chamber  present.  The  venter  begins  to  be  rounded 
on  this  living  chambered  part.  There  is  a  slig'ht  decrease  in  the  amount  of 
involution  at  the  same  time,  showing  that  this  is  in  its  gerontic  stage.  In  1 1 
other  specimens,  in  collection  of  the  Boston  Society  of  Natural  History,  and 
sent  me  by  Ward,  ranging  in  size  from  110  nnn.  in  diameter  to  nearly  the 
dimensions  of  the  specimen  last  described,  the  t}'pical  form  was  observed. 
No  tubercles  were  present,  and  the  first  lateral  saddles  were  very  narrow 
and  very  deeply  cut  by  almost  straight  and  very  long  marginal  lobes  and 
saddles. 

In  all  of  these  there  are  chevron  marks  more  or  less  shown,  and  the 
sutures  are  similar,  with  the  exception  first  mentioned.  The  first  three  lateral 
lobes  are  not  very  steeply  inclined  apicad,  and  the  fourth  lateral  is  nearly 
or  quite  two-thirds  as  long  as  the  third  lateral. 

Altogether  I  have  seen  perhaps  40  specimens. 

A  specimen  from  South  Dakota,  in  collection  of  the  Boston  Society  of 
Natural  History,  which  is  113  mm.  in  diameter,  shows  the  costal  and  the 
chevrons,  but  the  costse  are  quite  fold-like.  There  were  no  tubercles  on 
the  edires  of  the  ventral  zone  nor  on  the  umbilical  shoulders.  The  smallest 
part  of  the  outer  volution  was  about  30  mm.  and  the  widest  part  about  60 
mm.  from  line  of  involution  to  venter. 

Some  of  the  fragments  of  volutions  examined  must  have  1:)elonged  to 
shells  fully  15  inches  in  diameter,  the  size  of  the  specimen  from  New  Jersey 
figured  by  Morton  as  P.  placenta,  but  none  of  these  showed  the  gerontic 
degenerations  in  the  rounding  of  the  venter  as  in  his  figure.  The  wider 
separation  and  the  simpler  outlhies  of  the  sutures  found  in  his  figure  also 
occur  only  at  a  comparatively  early  stage  in  this  species.  The  ephebic 
staare  has  narrow  concave  venter  on  the  thick  shell  and  flattened  zone  on 
same  area  in  the  cast.  The  sides  are  perfectly  smooth,  with  faint  sigmoidal, 
almost  obsolescent,  costaj. 


PLACENTICERATID.E.  223 

Meek  figures  a  specimen  just  entering  upon  the  ephebic  stage,  and 
these  costte  are  faintly  indicated.  It  is,  in  fact,  difficult  to  see  them,  and 
thev  can  be  felt  better  than  seen  in  some  specimens.  The  costoe  are  often 
(juite  linear  and  distinct  on  the  shell  in  the  neanic  stage,  but  are  not  present 
before  or  after  this  stage.  The  divaricating  ridges  described  and  figured 
liv  Meek  as  lines  have  been  described  above  as  lateral  chevrons  with  the 
apices  pointing  orad  and  occurring  only  on  the  outer  thirds  of  the  sides  of 
the  shell.  They  are  very  plain  on  the  inner  layers  of  shell  and  faintly 
indicated  on  the  cast  and  entirely  independent  of  the  growth  bands.  At  an 
older  stage  (probably  the  metephebic  substage)  than  that  figured  by  Meek 
they  are  quite  broken  ov  interrupted  by  the  bands  of  growth  on  one  side 
where  the  nacreous  layers  are  preserved,  and  on  the  other,  in  wliit-h  part  of 
the  outer  layer  covers  them,  they  are  not  visible.  They  are  apparently 
characteristic  of  the  neanic  and  part  of  the  ephebic  stage.  The  venter 
retains  its  flatness  until  the  shell  is  very  large.  The  sutures  are  really  at 
considerable  distances  from  each  other,  but  the  saddles  are  so  deep  and  the 
lobes  so  long  and  narrow  that  the  external  outlines  are  approximated 
except  on  and  near  the  ventei*.  The  first  lateral  saddles  are  straight  and 
narrow,  and  there  is  consequently  a  band  on  either  side  of  the  venter  in 
casts  whicli  is  not  cut  up  by  intermingling  sutures.  On  breaking  down  a 
specimen  sent  me  by  Professor  Ward  the  young  at  diameter  of  11.13  mm. 
from  line  of  involution  to  venter  had  the  first  four  saddles  even  at  this 
early  stage  more  slender  and  more  deeply  cut  by  the  marginal  lobes  than  in 
tlie  specimens  supposed  to  be  young  of  I\  placenta  of  the  west  at  diameter 
of  2.')  mm.  The  lobes  and  saddles  were  also  longer  and  narrower  in 
proportion,  the  sutures  nearer  together,  and  the  branches  of  the  ventral  lobe 
larger  and  longer  and  the  ventral  saddle  with  larger  marginal  lobes  at 
exactly  corresponding  ages.  The  ventral  crenulations  or  tuberculations 
are  not  so  persistent  as  in  placenta  of  the  west,  since  they  disappear  in  all 
of  these  specimens  in  the  ephebic  stage. 

The  incomplete  living  chamber  is  about  one-half  of  a  volution  in 
length. 

The  first  volution  of  a  specimen  in  the  collection  of  the  Museum  of 
Comparative  Zoology,  from  Cliff'ord,  Nebraska,  has  a  depressed  rounded 
goniatitic  form  with  a  single  constriction  in  this  specimen  at  the  end  of 
the  first  quarter.     The  lateral  sutures  along  the  sides  have  the  broad  lateral 


224        PSErDOCERATITES  OF  THE  CRETACEOUS. 

saddles;  the  others  were  covered  and  could  not  be  seen.  The  only  exposed 
suture  immediately  preceding  the  constriction  has  entire  outline.s.  The 
ventral  lobes  are  moderately  deep  and  straight-sided,  with  large,  undivided 
siphonal  saddle.  The  first  lateral  saddle  is  rounded  and  broad,  but  entirely 
upon  the  venter,  as  is  also  the  first  lateral  lobe.  The  latter  is  also  rounded 
and  wide  at  base  and  not  so  deep  as  the  ventral  lobe.  The  second  lateral  is 
magnosellarian  in  outline  and  reaches  to  the  small  lobe  formed  on  the  line 
of  involution.  It  is  interesting  to  note  that  in  this  highly  degenerate  form 
of  the  Cretaceous  the  sutures  exactly  resemble  at  this  age  the  adults  of  the 
Primordialidfie,  which  have  undivided  siphonal  saddles,  and  the  volution 
on  section  has  the  semilunar  anarcestian  form  of  the  nepionie  stage  in 
Ammonitiufe." 

Near  the  end  of  the  first  volution  the  first  lateral  saddles  and  also  the 
magnosellarian  saddles  have  begun  to  show  minute  dividing  lobes.  The 
form  in  section  has  at  the  same  time  changed  to  helmet  shape  through  the 
elevation  of  the  venter.  The  zone  of  involution  at  this  age  begins  to 
increase  and  in  the  next  volution  extends  over  nearly  the  entire  side  of 
the  fir.st  whorl.  In  consequence  of  the  helmet  shape  and  flatness  of  the 
sides  the  involution,  which  is  about  two-thirds,  appears  to  be  greater 
than  at  any  subsequent  stage,  whereas  it  is  proportionately  less.  The 
ananeanic  substage  beg'ins  on  the  second  volution.  The  sides  become 
flatter,  more  convergent,  and  the  venter  is  narrowed  and  flattened  on  the 
cast  and  slightly  concave  on  the  shell.  In  the  metaneanic  this  change  is 
completed  by  the  rapid  increase  of  the  dorso-ventral  as  compared  with  the 
transverse  diameter.  The  venter  still  remains  quite  broad  and  does  not 
attain  the  narrow  aspect  of  the  adult  until  in  the  latter  })art  of  the  neanic 
stag'e  on  the  fourth  volution.  The  umbilical  zoue  begins  to  develop  in  the 
ananeanic  substage  and  steadily  increases  in  breadth  and  steepness  there- 
after. The  auxiliary  lobes  and  saddles  begin  to  appear  in  the  paranepionic, 
and  as  the  volution  increases  in  the  ventro-dorsal  diameter  more  of  them 
are  introduced  by  the  further  division  of  the  magnosellarian  saddle,  or 
rather  what  remains  of  this,  in  the  umbilical  zone.  The  process  of  division 
continues  throughout  the  neanic  stage,  the  additions  being-  made  internally 
on  the  umliilical  shoulders  and  zoue.     They  arise  as  simple  indentations 

and  grow  deeper  with  age,  the  digitations  being  introduced  gradually  by 

-  _— — . ^ .  _ 

"The  margin  of  the  maiuiscript  hears  a  large  "?"  opposite  this  sentence. — T.  W.  8. 


PLACENTICERATID.E.  225 

minute  inflections  of  the  outlines.  The  saddles  are  not  so  long  as  to  inter- 
fere with  deciphering  the  outlines  of  the  lobes  until  the  fourth  volution  is 
reached  and  the  anephebic  substage  begins.  Before  this  the  sutures 
resemble  more  those  of  P.  bolli,  ha\'ing  shorter  saddles  and  proljably  at  still 
earlier  stages  they  are  even  more  like  those  of  this  species,  being  pi'opor- 
tiouately  shorter  and  with  simpler  digitations.  There  are  nine  lobes  present 
on  the  last  quarter  of  the  third  volution.  The  three  principal  lobes  have 
their  usual  proportions,  and  the  ventral  lobe  is  nearly  the  same  as  in  the 
adult,  but  the  siphonal  saddle  is  not  so  prominent,  and  the  minor  saddles 
on  the  sid^  of  this  are  also  much  smaller  and  more  nearly  of  the  same  size. 
There  are  six  lobes  on  the  lateral  zone,  a  seventh  on  the  shoulder,  and  two 
on  the  umbilical  zone.  The  saddles  are  all  distinctly  bifid,  except  the  tenth, 
which  is  not  yet  differentiated.  The  lobes  are  all  of  the  trifurcate  type, 
except  the  nintli,  which  is  not  fully  developed  and  is  single  or  unsym- 
metrical.  The  lobes  and  saddles  greatly  increase  in  complication  of  outline 
and  become  larger  and  lai'ger,  but  the  number  remains  stationary  on  the 
fifth  volution.     Meek"  figures  a  very  large  suture  with  twelve  lobes. 

Tubercular  elevations  make  their  appearance  on  the  edges  of  the 
ventral  zone  in  the  ueanic  stage,  but  they  are  more  perceptible  to  the  touch 
than  to  the  eye.  The  widely  separated  sigmoidal  costas  are  more  distinct, 
but  the  deep  apical  bend  is  only  one-half  developed  and  ends  abruptly  in 
some  with  a  faint  tubercle.  The  ventral  part  of  the  bend  is  apparently 
absent  on  the  fourth  volution,  but  subsequently  appears  more  decidedly  on 
the  last  quarter  of  this  volution.  Internally  the  oral  bend  of  these  costse 
is  also  deficient  in  the  neanic  stage,  appearing  to  be  better  developed  in 
an  ephebic  substage.  Nevertheless,  when  one  looks  at  the  volution,  he  is 
apt  to  see  only  the  inner  half  of  the  deeper  apical  bend.  The  chevron-like 
folds  are  present  on  the  shell  in  the  later  neanic  substages  and  may  come 
in  earlier.  A  line  of  very  faint,  liprdly  perceptible,  tubercles  appears  on 
the  umbilical  shoulder  on  the  fifth  volution  in  an  ejjhebic  substage. 

I  have  been  as  minute  in  my  descriptions  as  the  specimen  in  hand 
permitted,  because  the  presence  of  these  indistinct  tubercles  and  costa-  in 
the  neanic  and  early  ephebic  substages  show,  together  with  the  more  widely 
separated  sutures  and  broader  venter,  that  the  young  are  quite  similar  to 
those  oi  placenta  and  have  also  traces  of  their  affinity  with  the  more  heavily 

aMon.  U.  S.  Geol.  Surv.  Terr.,  Vol.  IX,  p.  466. 
MON   XLIV — 03 1.5 


226        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

tuberculated  and  stouter  forms  P.  bolli.  The  saine  characters  also  show- 
that  these  species  are  not  identical,  since  they  are  not  so  strongly  developed 
at  any  stage  as  in  other  species,  and  are  succeeded  by  distinct  sutures  in 
the  nearly  full-grown  shells.  This  study  suggests  also  that  the  western 
species  was  derived  from  the  eastern  form. 

A  specimen  j)urchased  from  Professor  Ward,  locality  Bad  Lands,  near 
Black  Hills,  South  Dakota,  shows  the  typical  sutures  and  form  of  whitfieldi. 
The  first  lateral  saddles  in  the  ephebic  stage  have  the  usual  three  nearly 
equal  marginal  saddles  and  lobes,  and  there  are  no  tubercles  nor  any  costse 
appreciable  to  the  eye  at  diameter  from  lines  of  involution  to  venter  of 
101  mm.  These  sutures,  however,  have  one  peculiarit}',  probably  of  essen- 
tial service  to  this  investigation.  In  so  far  as  the  first  two  saddles  and 
lobes  are  concerned,  they  are  appreciably  distinct,  the  first  saddles  being 
entirely  free.  The  remaining  parts  of  the  sutures  overlap  more  or  less, 
as  in  almost  all  of  this  species.  In  the  anephebic  substage,  or  last  of 
neanic  stage,  however,  the  diameter  of  volution  being  33.5  nun.,  the  costse 
are  apparent  and  have  the  usual  form,  but  are  very  faint.  The  chevrons 
are  especially  well  shown  in  the  fossil,  although  not  more  prominent  than 
in  many  other  specimens.  They  were  plainly  seen  on  this  fragment, 
broken  out  of  the  larger  volution,  and  there  appeared  to  be  some  connection 
between  these  at  their  line  of  convergence  and  the  indistinct  longitudinal 
ridge  or  trace,  which  is  obviously  the  centran  lateral  ridge  seen  in  some 
older  shells.  The  sutures  are  similar  to  those  of  the  adult  at  the  diameter 
of  24  mm.  from  lines  of  involution  to  venter,  but  they  are  easily  separable 
by  the  eye. 

The  earlier  probably  paraneanic  substage  dissected  out  from  this  was 
perfect  and  measured  2(>.5  mm.  in  diameter  of  the  coil.  The  larger  end 
of  the  volution  in  this  was  15  mm.  from  line  of  involution  to  venter,  and 
when  the  volution  was  about  11  mm.  in  same  diameter  the  chevrons  and 
costs  and  excessively  faint  longitudinal  ridges  began  to  appear.  There 
were  as  many  as  three  of  these  along  the  centran  lateral  aspect  of  the 
volution  and  .shorter  but  discontinuous  ones  arising  from  the  chevrons. 
These  could  only  be  seen  by  careful  and  prolonged  observation  of  the 
nacreous  layer,  which  was  preserved  on  one  side.  The  sutures  were  less 
crowded  than  in  the  young  one  above  described  and  favorable  for  obser- 
vations at  diameter  just  noted.     There  were  ten  lobes  in  all,  including  one 


PLACENTICERATID.E.  227 

on  the  line  of  involution.  Six  were  on  the  lateral  zone,  one  on  the  sharply 
defined  umbilical  shoulder,  and  three  on  the  umbilical  zone.  The  last  sad- 
dle showed  a  distinct  marginal  lobe,  the  next  saddle  single,  the  succeeding 
saddles  were  also  bifid  and  had  entire  outlines,  the  fourth  had  begun  to 
show  marginal  digitations,  and  the  remaining  saddles  were  more  or  less 
deeply  cut,  having  approximately  the  forms  of  the  ephebic  stage,  but  being, 
of  course,  much  simpler.  The  outlines  of  all  of  them  were  free  except 
those  of  third  and  fourth  saddles  and  those  of  the  third  lateral  lobe.  The 
umbilical  lobe  is  probably  entire,  as  is  the  next  lobe;  the  eighth  is 
symmetricallv  trifid,  the  next  from  its  position  on  the  umbilical  shoulder  is 
unsymmetrically  trifid,  the  next  lobe  on  the  side  is  symmetrically  trifid 
again.  The  remaining  lobes  show  ephebic  division  already  defined  but 
simpler  than  in  the  adult,  and  the  same  is  true  also  of  the  ventral 
lobe  and  saddle,  and  the  bare  spaces  on  the  cast  on  either  side  of  the 
venter  would  be  as  conspicuous  as  in  the  later  stages  if  the  sutures 
were  as  close  together.  One  thing  is  noticeable  in  this  specimen;  the 
slightly  younger  sutures  on  the  same  volution  are  for  a  time  slightly  closer 
than  the  succeeding  ones,  owing  to  a  temporary  decrease  in  the  rate  of 
growth  of  the  shell.  This  specimen  had  svitures  quite  diff"erent  from  the 
sutures  of  the  small  specimen  above  described,  in  which  at  the  same  age 
there  were  approximating  and  even  decidedly  overlapping  outlines,  as  in 
the  adult.  The  outlines  themselves,  however,  were  about  the  same  in  both 
specimens,  so  that  the  difterences  were  merely  those  of  the  slower,  less 
vigorous  growth  of  the  forms  as  compared  with  that  now  being  described. 

At  the  beginning  of  this  volution,  when  the  diameter  from  lines  of 
involution  to  venter  is  7  nun.,  the  umbilical  zone  is  just  beginning  to  be 
formed.  The  ventral  saddle  at  this  time  is  just  beginning  to  sliow 
digitations  on  its  sides,  and  is  broad  and  large  with  flat  concavity  across 
the  venter.  The  first  lateral  saddle  is  distinctly  trifid,  the  second  and  third 
laterals  with  club-shaped  bases  and  almost  entire,  showing  only  the  faintest 
possible  trace  of  the  median  marginal  lobe  that  divides  tliem  in  the 
succeeding  sutures;  the  fourth  lateral  has  this  marginal  lobe  more  distinct, 
but  still  very  small,  and  the  remaining  saddles  are  entire  with  somewhat 
flattened  basal  lines. 

The  arras  of  the  ventral  lobe  and  the  tops  of  the  first  and  second  and 
third  laterals  are  unsymmetrically  trifid,  the  fourtli  lateral  is  just  beginning 


228        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

to  have  a  median  marginal  division  and  is  bifid,  the  remaining  lobes  being 
entire  and  very  small  and  narrow.  The  trend  of  the  sutures  is  about  the 
same  as  in  adults,  but  the  bend  at  the  fourth  lateral  saddle  is  more  abrupt, 
the  fourth  lateral  lobe  being  a  scant  one,  about  one-half  the  length  of  the 
third  lateral.  This  proportion  begins  to  alter  soon  after  this,  and  approxi- 
mates to  that  of  the  adult  before  the  end  of  this  volution.  The  number  of 
lobes  and  saddles  is  the  same;  they  are  simply  smaller  in  size  and  more 
primitive  in  outline.  A  very  slight  amount  of  exposure  acts  upon  these 
sutures  and  alters  the  outlines,  destroying  the  marginal  lobes  and  saddles. 
At  this  time,  i.  e.,  7  mm.  in  diameter,  the  sutures  are  somewhat  more  primi- 
tive on  the  left  than  on  the  right  side  of  the  volution,  an  irregularity  that 
subsequently  becomes  less  noticeable.  There  is  probably  nothing  abnormal 
in  this,  as  it  is  rare  in  any  animal  to  find  the  two  sides  exactly  similar. 
The  costse  begin  very  early  when  the  volution  is  about  7  mm.  in  diameter 
from  lines  of  involution  to  ventei-. 

In  the  ananeanic  substage,  when  the  volution  is  4  to  5  mm.  in  diameter, 
the  ventral  zone  is  channeled,  as  in  later  stages,  and  sensibly  broader  in 
proportion.  The  form  of  the  sutures,  etc.,  is  the  same,  but  the  digitations 
are  less  noticeable.  The  first  lateral  saddle  on  the  most  perfect  side  of  this 
volution  is  faintly  trifid,  all  the  remaining  saddles  are  entire  and  club- 
shaped  except  the  smaller  ones  beyond  the  fourth,  which  are  now  plainly 
seen  as  mere  inflections  of  the  outlines  of  the  magnosellarian  saddles.  The 
arms  of  the  ventral  lobe  are  single,  the  first  and  second  laterals  are  beginning 
to  show  trifid  tops,  while  the  third  is  broader  and  more  club  shaped,  and 
shows  four  nearly  equal  marginal  lobes  just  beginning  to  appear.  The 
ventral  saddle  is  broad  with  concave  base,  the  dependent  marginal  saddles 
being  absent.  There  were  nine  lobes  at  this  stage,  but  the  ninth  on  the 
line  of  involution  was  very  minute. 

The  next  break  exposed  an  earlier  age  in  the  ananeanic  substage  on 
the  first  quarter  of  the  same  volution.  The  venter  had  just  become  flattened 
and  the  edges  of  this  zone  are  faintly  crenulated  on  the  cast,  owing 
apparently  to  the  presence  of  extremely  fold-like  cost*  which  cross  the 
venter.     These  are  so  indefinite  that  they  were  perceived  with  difliculty. 

The  sutures  are  extremely  instructive.  The  ventral  lobe  is  as  deep 
and  as  broad  as  the  ventral  zone;  the  ventral  saddle  is  very  small  and 
divided  by  a  siphonal  lobe.     The    sides  of  the  first    lateral  saddles  are 


PLACENTICERATID.E.  229 

straight,  and  on  the  edges  of  the  ventral  zone  the  bases  are  entire  and 
rounded.  The  tirst  and  second  lateral  lobes  and  the  first,  second,  and  third 
lateral  saddles  appear  as  inflections  on  the  inner  sides  of  the  broad 
nepionic  first  lateral  saddles.  The  third  lateral  lobes  occupy  the  positions 
and  are  obviously  the  direct  local  representatives  of  the  primitive  primor- 
dialian  lateral  lobes.  A  large  saddle,  the  primitive  magnosellarian  saddle, 
occupies  the  inner  part  of  the  sides  and  two  minute  marginal  lobes  and 
saddles  are  apparent  on  this.  The  first  marginal  saddle,  the  forerunner 
of  the  fourth  and  fifth  saddles,  is  flat  on  the  base  and  beginning  to  show 
an  initial  median  marginal  lobe;  the  future  fourth  lateral  lobe,  the  inner 
saddle,  has  similar  form  but  is  still  entire.  This  and  the  other  specimens 
show  that  the  great  length  of  the  third  lateral  lobes  and  the  apical  bend  in 
the  sutures  and  septa  of  adults  are  due  to  the  retention  of  nepionic  characters 
and  that  the  great  complication  in  the  details  of  the  outlines  and  the  large 
number  of  lobes  and  saddles  are  based  upon  primitive  neijionic  outlines. 
This  is  also  apparent  in  the  internal  double  curvature  of  the  septa,  which 
are  concave  along  the  center  and  convex  like  those  of  most  Ammonitinge 
only  at  the  dorsal  and  ventral  lobes. 

A  fine  young  specimen.  No.  18936,  U.  S.  National  Museum,  Upper 
Missouri,  enables  me  to  add  the  following:  Whole  diameter  is  55  mm., 
and  the  fourth  volution  is  about  completed.  On  the  early  part  of  this 
volution  the  sutures  are  the  same  as  in  the  young  specimen  above 
described.  The  characteristic  deeply  cut  saddles  and  lobes  of  the  western 
fonn  are  already  beginning  to  appear"  and  the  first,  second,  and  third 
lateral  lobes  have  about  the  same  proportions  as  in  the  adult,  but  the  fourth 
lateral  is  only  about  half  as  long  as  the  third  lateral  lobe.  The  sutures  in 
this  specimen  are  not  so  distinctly  separated  as  in  the  young  one  at  same 
age  referred  to,  and  are  almost  as  closely  intermingled  as  in  the  adult. 
The  usual  band  free  of  sutures  occurs  on  each  side  of  the  venter.  On 
breaking  down  this  specimen  the  sutures  on  the  last  quarter  of  the  tlnrd 
volution  were  found  to  be  more  distinctly  separated,  the  margins  becoming 
simpler,  but  the  peculiar  bands  free  of  sutures  on  either  side  of  the  venter 
are  still  present,  and  the  species  could  hardly  be  mistaken  even  at  this 


"  The  external  shell  is  preserved  in  the  umbilicus,  but  there  are  no  tubercles,  and  venter  is 
smooth  on  the  cast  of  this  part.  The  outer  layer  of  shell  of  the  last  quarter  of  fourth  volution  is 
preserved  and  shows  same  markings  as  above  described  at  about  same  age  in  young  specimen  from 
Nebraska. 


230        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

earl}'  stage  on  account  of  the  much  compressed  wholly  smooth  volution 
and  naiTOw  conca\-e  -s'enter  with  slightly  elevated  acute  ridges  on  either 
side  on  the  cast.  At  this  age  inner  saddles  assume  a  primitive  rounded 
form  with  expanded  base  and  one  marginal  central  lobe;  the  inner  lubes 
are  trifid.  Two  specimens  in  the  collection  of  the  Boston  Society  of 
Natui-al  History,  collected  by  Prof.  W.  CI.  Crosby,  have  the  typical 
characters  and  form  of  P.  whitfieldi  and  are  devoid  of  tiibercles.  The 
sutures  were  not  very  clearly  made  out.  The  matrix  has  the  aspect 
of  an  arenaceous  I  limestone,  color  light  brown.  The  largest  specimen 
from  Fort  Collins,  Colo.,  is  l)-i5  mm.  and  the  smaller  one  from  El  Paso 
County,  Colo.,  84  mm.  in  whole  volution.  One  specimen  in  the  collection 
of  the  Boston  Society  of  Natural  History  reaches  265  mm.  in  diameter  and 
has  a  concave  ventral  zone  on  both  shell  and  cast  at  end  of  outer  volution. 
There  are  excessively  faint  tubercles  along  the  umbilical  shoulders  but  no 
traces  of  them  on  the  edges  of  the  ventral  zone,  either  on  shell  or  cast. 

The  shell  on  this  specimen  and  on  several  others  is  sufficiently  perfect 
to  show  that  there  are  the  following  parts.  An  outer  opaque  probably 
porcellaneous  part  of  several  layers,  next  a  middle  part  with  more  or  less 
of  luminous  red  coloration,  also  of  several  layers,  and  an  inner  part,  also  of 
several  layers,  with  the  usual  iridescence  of  nacreous  shell 

Two  specimens  from  Loup  Fork,  Nebr.,  in  the  Museum  of  Comparative 
Zoology,  show  the  typical  large  siphonal  saddle  with  dependent  marginal 
saddles  of  'whitfieldi.  One  of  them  belongs  to  the  parephel^ic  stage  of  a 
shell  having  at  the  same  time  concave  venter  on  both  cast  and  shell  with 
very  faint  tubercles,  and  the  other  and  the  two  descnbed  next  below 
represent  the  gerontic  stage  of  a  shell  of  ver}-  large  size  of  the  same 
species,  with  flattened  venter  on  the  cast  and  very  faint  concave  zone  on 
the  shell,  but  no  signs  of  tiibercles  on  this  part.  The  umbilical  shoulders 
were  destroyed.  In  both  of  these  specimens  from  Kansas  the  ventral 
branches  of  tirst  lateral  saddles  did  not  reach  the  edges  of  the  venter  and 
the  same  smooth  band  appeared  on  either  side  of  this  part  as  in  other  forms 
of  this  group.  I  can  not  at  present  separate  them  frojn  whitfiekJi  upon  the 
basis  of  their  slight  tuberculations,  since  faint  tubercles  are  apt  to  be 
present  at  some  stage  even  in  typical  forms  of  this  species  A  fine 
specimen  from  Nebraska,  diameter  228  ram ,  and  covered  with  beautiful 
nacre,  shows  chevron  markings   and  has  concave  ventral  zone  and  faint, 


PLACENTICERATID.E.  231 

ratlier  uncertain  indications  of  tubercles  that  may  have  existed  on  the  outer 
shell,  although  the  inner  line  on  the  umbilical  shoulders  is  plainly  shown 
on  the  nacre  of  the  last  volution.  These  last  are  obviously  confined  to  this 
volution  of  the  ephebic  stage,  since  they  are  not  present  on  the  inner 
volutions,  which  are  covered  by  the  thick,  opaque  outer  layer  of  the  shell. 
This  settles  the  fact  that  these  tubercles  may  appear  ver}-  late  in  the  life  of 
this  species.  They  are  small  and  wide  apart  on  this  specimen  when  the 
volution  from  line  of  involution  to  the  venter  is  60  mm.,  and  are  not 
present  on  the  external  shell  in  that  part  of  the  same  volution  which  is 
about  a  centimeter  apicad  across  a  break  in  the  fossil.  There  are  fine 
transverse  wrinkles  on  the  nacreous  layer  in  the  ventral  zone  of  this  shell. 
A  large,  much  crushed  fossil  from  Loup  Fork,  Nebr.,  also  collected 
by  Dr.  Sternberg,  is  215  mm.  in  diameter  and  has  the  external  shell  well 
preserved  and  as  usual  very  thick,  especially  on  the  umbilical  shoulders. 
Faint  tubercles  are  present  on  the  last  volution  and  are  also  preserved  on  a 
remnant  of  shell  belonging  to  a  volution  which  has  been  broken  away. 
Such  small  tubercles  as  these  might  be  present  on  a  shell  and  yet  be  absent 
on  a  cast. 

A  fine  specimen  in  the  National  Museum,  with  nacreous  layer,  from 
southern  Colorado,  and  having  typical  sutures  of  the  western  form  and  also 
identical  in  other  respects,  has  a  diameter  of  136  mm.  and  shows  faint 
tubercles  on  the  nacreous  layer.  The  volution  is  65  mm.  in  diameter  from 
line  of  involution  to  venter,  when  the  first  tubercle  appears.  This 
specimen  makes  It  possible  to  say  definitely  that  these  appear  in  the 
ephebic  stage,  probably  metephebic  substage. 

One  specimen,  from  Black  Hills  region,  in  the  collection  of  the  Boston 
Society  of  Natural  History,  .shows  faint  tubercles  on  umbilical  shoulders 
when  the  diameter  is  less  than  100  mm.,  and  there  are  faint  but  perfectly 
defined  minute  tubercles  on  either  side  of  the  venter.  Another  specimen  in 
the  same  collection  and  from  the  same  locality  has  a  diameter  of  305  mm. 
It  is  without  living  chamber  and  has  the  nacreous  layer  in  part  preserved. 
There  are  faint  tubercles  on  the  umbilical  shoulders  of  the  next  imier  and 
part  of  the  outer  volution.  The  sides  have  three  obscure  broad  longi- 
tudmal  folds  or  ridges  in  the  gerontic  stage.  There  are  no  tubercles  on 
the  edges  of  the  ventral  zone.  This  zone  continues  to  be  very  faintly 
concave,  even  on  the  last  part  of  the  outer  volution.     The  gerontic  stage 


232        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

beo-ins  witli  a  slig-ht  transverse  constriction,  after  which  the  transverse 
diameters  increase  considerably  and  the  vokition  is  stouter  and  larger. 

The  largest  specimen  so  far  recorded  is  in  the  University  Musemn  in 
New  Haven  (locality,  Bad  Lands,  South  Dakota).  This  has  been  meas- 
ured b}^  Dr.  C.  E.  Beecher,  who  also  very  courteously  sent  me  a  sketch  and 
notes  on  its  characteristics.  The  diameter  of  the  entire  fossil  is  630  mm. 
(24f  inches).  The  ventro-dorsal  diameter  of  apei'ture  from  line  of  involu- 
tion to  venter  is  300  mm.,  and  the  transverse  150  mm.,  showing  how  much 
the  volution  has  broadened  in  this  extreme  gerontic  stage.  The  first 
quarter  of  outer  volution  has  a  flat  venter  8  mm.  wide,  the  edges  rounded. 
The  living  chamber  is  perfect  and  occupies  one-half  of  a  volution,  showing 
no  decrease  in  length  as  compared  with  smaller  specimens.  There  is,  how- 
ever, the  usual  decrease  in  the  amount  of  involution  of  the  whole  of  the 
outer  volution.  The  venter  loses  its  flatness  entirely  on  the  second  quarter 
of  the  outer  volution  and  on  central  parts  of  living  chamber,  becomes 
rounded,  and  the  sides  then  become  gibbous  at  a  short  distance  inside  the 
venter,  as  is  not  uncommon  in  old  age.  There  is  a  tendency  to  resume  the 
form  of  syrtale  and  of  its  own  earlier  stages.  Near  the  aperture  the  geron- 
tic flat  zone  noticed  in  other  specimens  returns  upon  the  centran  part  of 
the  venter,  but  the  latter  still  remains  rounded  with  the  same  gibbous  out- 
line to  the  outer  parts  of  the  sides.  The  aperture,  as  desci'ibed  in  other 
specimens,  has  a  short,  broad  rostrum  and  low,  broad  lateral  crests. 

Locality:  Nebraska;  South  Dakota;  Colorado. 

Aye:  Fort  Pierre  grouji,  Upper  Cretaceous. 

Placenticeras  whitfieldi  variety  tuberculatum  Hyatt. 

PI.  XLVII,  fig.  5. 

I  have  so  far  seen  only  three  shells  ft-om  Bad  Lands,  South  Dakota, 
having  a  very  faint  line  of  median  lateral  tubercles  both  on  cast  and  shell, 
as  well  as  minute  denticles  on  the  sides  of  the  venter  and  tubercles  on  the 
umbilical  shoulders.  The  two  outer  rows  disappear  at  the  end  of  the  neanic 
stage,  when  the  shell  is  about  80  mm.  in  diameter.  These  are  obviously 
transitional  to  F.  pseudoplacenta,  but  have  much  finer  tuberculations  and 
more  complicated  sutures. 

Locality:  Bad  Lauds,  South  Dakota. 

Age:  Yort  Pierre  group.  Upper  Cretaceous. 


PLACENTICERATID^.  233 

Placenticeras  spillmani  n.  sp.  Hyatt. 
PI.  XL VII,  figs.  6-8. 

This  species  is  founded  upon  a  fragment,  No.  4,  in  the  collection  of  the 
Academy  of  Sciences  of  Philadelphia;  but  this  is  so  distinct  from  any 
species  of  Placenticeras  known  to  me  that  I  venture  to  describe  it  here. 
This  was  in  same  tray  with  three  fragments  of  Sphenodiscus  labeled  "Spill- 
man  Coll.  Loc.  Mi.ssissippi." 

The  estimated  diameter  of  the  volution  is  80  mm.;  tiie  actual  ventro- 
dorsal diameter  measured  along  the  exposed  septum  from  dorsal  lobe  to 
ventral  lobe  is  48  mm.;  and  actual  transverse  diameter  is  about  40  mm. 
through  the  dorsal  lobe.  It  has,  therefore,  a  much  stouter  volution  at  the 
same  age  than  its  near  allies,  placenta  or  stantoni,  and  the  venter  is  broad  in 
proportion,  being  9  mm  in  width,  flat,  and  with  low  tubercles  on  either  side 
about  14  mm.  apart.  The  fragment  is  onlj-  the  cast  of  the  outer  parts  of 
two  living  chambers,  and  whether  there  were  internal  rows  of  tubercles 
could  not  be  determined,  but  the  sides  have  the  flattened  aspect  of  species 
that  do  not  habitually  have  a  median  lateral  row  of  tubercles.  The  sutures 
are  closely  similar  to  those  of  syrtale;  they  have  broad,  rather  short,  solid 
saddles,  with  short  marginal  saddles,  the  lobes  narrow  and  broad,  only  at 
the  apical  ends.  The  outer  part  of  the  septum  is  more  deeply  concave  than 
in  placenta  and  the  lobes  and  saddles  are  less  complex  in  outline.  There  is 
a  cast  of  one  chamber  in  the  collection  of  Yale  University,  said  to  be  from 
Burlington,  N.  J.,  with  a  similar  broad  venter,  that  may  be  the  young  of 
this  species.  The  dorso-ventral  diameter  measured  in  same  way  as  above 
is  24  mm.,  and  transverse  diameter  is  about  18  mm.  There  is  aLso  a  cast 
from  Musselshell  Creek,  Idaho,  having  a  very  broad  venter.  This  belonged 
to  a  much  older  and  larger  .shell  with  very  different  sutures. 

Locality:  Burlington,  N.  J.;  Mississippi. 

Placenticeras  ?  telifer  (Morton). 

Ammonites  telifer  Morton,  1834,  Synop.  Organic  Reniain.s,  pi.  2. 
Ammonites  (Placenticeras)  telifer  Whitfield,  1892,  Mon.  U.  S.  Geol.  Survey.  Vol. 
XVIIl,  pi.  41. 

After  examining  the  fragments  of  this  species  in  the  collection  of  the 
Academy    of    Sciences,    Philadelphia,   I    am     unable    to    determine    with 


234        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

certainty  whethei-  this  is  a  species  of  this  genus  or  not,  and  the  details  of 
the  sutures,  so  far  as  my  hasty  examination  went,  were  too  imperfect  to 
enable  me  to  make  a  reasonable  guess  with  regard  to  their  affinities. 

Locality:  New  Jersey. 

Age:  Upper  Cretaceous. 

Placenticeras  ?  FALLAX  Castillo  and  Aguilera 

Placenticeras  ?  fall  ax  Castillo  aud  Aguilera,  1895,  Bol.  Codi.  geol.  de  Mexico,  No. 
I,  p.  17,  pi.  9. 

This  species  is  here  mentioned  because  it  is  likel}-  to  be  quoted  as  a 
species  of  this  genus,  whereas  both  the  remarks  of  the  authors  and  tlie 
figures  show  that  it  should  be  quoted  as  probably  not  a  membei-  of  this 
genus.  The  authors  consider  the  sutures  as  placenticeran,  but  xerj  rightly 
regard  the  form  as  more  like  that  of  Phylloceras.  I  have  not  as  yet  seen  a 
specimen  of  this  genus  that  has  such  a  rounded  volution  even  in  the  gerontic 
stage,  and  this  Mexican  specimen  was  only  104  mm.  in  diameter. 

Locality:  Mexico. 

Age:  Lower  Cretaceous  1 

Placenticeras  ebrayi  (de  Loriol). 

Amaltheus  ehray!  de  Loriol,  1882,  Mem.  Soc.  Pal.  kSuisse,  Vol.  IX.  PI.  I. 
Placenticems  ehrayi  Kossmat,  1895,  Beitr.  Pal.  und  Geol.  Oesterreicli-Unganis  uud 
des  Orients,  Vol.  IX,  p.  170. 

This  figure  shows  a  large  and  aged  specimen  of  250  mm.  in  diameter. 
The  anagerontic  substage  is  given  ujjou  the  first  part  of  the  outer  volution, 
and  during  this  time  the  venter  remains  flattened  and  has  large  alternating 
tubercles  of  the  usual  elongated  form  on  either  side,  but  the  edges  of  this 
zone  are  not  sinuous.  There  are  fold-like  single  cost*  appearing  in  this 
substag'e,  and  these  are  prominent,  but  have  no  tubercles  if  the  views  are 
correct.  These  single  folds  are  continued  in  the  metagerontic  substage 
when  the  ventral  line  of  tubercles  disappear  and  three  lines  of  lateral 
tubercles  appear  for  the  first  time  on  the  costa?.  In  the  paragerontic 
substage  these  tubercles  disappear,  first  the  outer,  then  the  inner  lines,  and 
then  the  central  line.  The  folds  also  tend  to  disappear  aud  the  venter  is 
seen  to  be  completely  rounded  and  smooth  in  this  substage  and  the  involu- 
tion has  become  considerably  diminished,  judging  from  the  aspect  of  the 


PLACENTICERATID.E.  235 

umbilicus.  The  gerontic  tubercles,  together  witli  the  ventral  line  of 
tubercles,  make  u])  four  rows,  one  more  than  appears  in  any  other  shell  of 
this  genus.  The  sutures  were  observed  only  in  the  anagerontic  substage, 
but  they  are  distinctly  separated  and  have  obviously  not  lost  then-  ephebic 
characters. 

There  may  be  but  two  secondary  laterals  derived  from  the  primitive 
first  lateral  saddle,  or  there  may  be  three ;  one  can  not  tell  with  exactitude 
from  the  drawings  and  descriptions.  The  general  aspect  of  this  shell  is  in 
favor  of  association  with  the  species  of  Placenticeras,  but  the  extra  line  of 
tubercles  in  the  old,  the  fold-like,  almost  straight  costse,  and  the  possibility 
that  there  ai'e  only  two  secondary  saddles,  the  first  and  second  laterals,  niake 
the  generic  reference  doubtful.  The  outlines  of  these  sutures  remind  one 
strongly  of  P.  warthi  Kossmat,  and  in  this  species  there  is  also  the  same 
difficultv  in  making  out  whether  the  first  lateral  is  single  or  double.  The 
ventral  lobe  is  deep  and  narrow,  as  in  P.  uhligi,  but  the  siphonal  saddle  is 
small.  The  shell  is  apjjarently  smooth  in  the  ephebic  stage,  as  in 
warthi,  etc. 

Age:  Gault  of  Cosne. 

Placenticeeas  warthi  Kossmat. 

Aimaonite«  orhignyanKH  Stoliczkii.  1860,  Pal.  liulica.  Vol.  I,  pi.  48,  fig.  2. 
Placenticet'ttii  imrthi  Kossmat,  1895,  Beitr.  Pal.  und  Cieol.  Oesterreich-Ungarns  und 
des  Orients.  Vol.  IX,  pi.  20,  fig.  8. 

This  species  is,  as  stated  by  Kossmat,  quite  distinct  either  from  orhig- 
nyanus  of  Geinitz,  or  syrtalis,  var.  orhignyanus  of  Schliiter.  Kossmat's  text 
clearly  states  these  distinctions,  but  he  gives  both  of  these  names  in  his 
synonymy  as  in  part  belonging  to  this  species,  and  on  this  fact  we  differ. 
The  young  as  figured  in  section  by  Stoliczka  has  a  very  broad  venter  in 
the  ananeanic  substage  and  the  broad  venter  is  retained  throughout  the 
neanic  stage. 

The  sutures  are  exceptional,  the  ventral  saddle  distinct  from  any  other 
species  of  this  genus,  and  there  are  so  slight  differences  between  the  princi- 
pal lateral  saddles  and  the  auxiliaries  that  one  can  not,  according  to 
Kossmat's  figures,  draw  a  definite  line  between  the  auxiliaries  and  the 
principal  saddles.  Kossmat  counts  the  two  arms  of  the  first  lateral  as  two 
saddles,  but  describes  these  as  having  arisen  from  division  of  the  firsf 


236        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

lateral,  and  his  figure  shows  this.  He  consequently  considers  the  si)ecies 
as  having  four  principal  lateral  saddles,  whereas  they  should  Ije  counted  as 
three.  Stoliczka's  figure  of  the  older  specimen  in  his  Fossil  Cephalopoda  of 
Cretaceous  Rocks  of  Southern  India  also  shows  distinctly  the  three  princi- 
pal saddles.  Kossmat  considers  this  identical  with  the  American  P.  syrtale, 
but,  as  has  been  noted  elsewhere,  P.  tamulicum,  and  especially  schluteri,  are 
more  like  the  former.  The  absence  of  all  except  the  ventral  line  of  tuber- 
cles and  the  broad,  fold-like  costse,  broad  venter,  and  stout  whorls  are  as 
peculiar  as  the  sutures  in  warthi.  In  the  ragged  aspect  of  the  sutm-es  and 
broad,  flat  venter,  this  s^jecies  has  some  resemblance  to  P.  stantoni  of  the 
Colorado  group.  This  favors  the  view  that  this  species  occurs  in  India 
somewhat  earlier  (in  the  lower  Utatur  group,  which  is  placed  by  Kossmat 
in  the  Cenomanian)  than  its  representative  in  this  country.  This  evidence 
is  in  favor  of  the  view  stated  by  Stanton  and  others  that  the  Colorado  is  the 
equivalent  of  the  Turonian. 
Age:  Cenomanian. 

Placenticeras  memoria-schloenbachi  Laube  and  Bruder. 

Placenticeras  m&m.oria-schloe'nbacld    Laube    and    Bruder,    1887.  Palfeontogr. ,  Vol. 
XXXIII,  pi.  23. 

This  species  has  a  diameter  of  198  mm.;  it  is  smooth  witli  the  excep- 
tion of  a  single  inner  row  of  small  tubercles  on  the  umbilical  shoulder. 
The  umbilical  zone  is  well  shown  in  figure,  and  the  ventral  zone  very  nar- 
row and  smooth  on  the  cast.  The  parts  of  two  sutui'es  shown  haA-e  very 
simple  outlines  and  are  wide  apart  even  in  what  is  evidently  the  parephebic 
or  anagerontic  stage  of  this  species. 

The  outlines  are  probably  more  or  less  worn  and  have  lost  their  digi- 
tations  in  part,  but  could  not  in  any  event  probably  have  been  as  closely 
approximated  as  in  species  like  placenta  or  whitfieldi.  Laube  and  Bruder 
consider  that  the  sutures  are  similar  to  those  of  Placenticeras  requieniamim 
(d'Orbigny,  Ten-.  Jurass.,  pi.  93,  fig.  4),  but  this  species  does  not  belong  to 
this  genus. 

Age:  Turonian. 


PLACENTICERATID^.  237 

Placenticeras  depressum  u.  sp.  Hyatt. 

I^acenticeras  syrtaJe  Grossouvre  (jjars),  1893,  Ammonites  Craie  superieure,  p.  128, 

pi.  6,  fig.  2  oul}',  and  pi.  7,  fig,  1. 
Ammonites  syrtalis  Schluter  (pars),  1871,  Palaeontogr. ,  Vol.  XXI,  pi.  14,  figs.  9  and 

10  only. 

This  French  and  German  species  is  undoubtedly  a  very  close  ally  of 
gnadahqm  and  is  called  variety  guadalupee  by  both  authors,  who  suppose  it 
to  be  identical  with  the  American  species  of  the  same  name.  The  latter, 
however,  has  not  the  costse  in  the  young  shown  in  the  umbilicus  as  figured 
by  Grossouvre  on  pi.  7,  and  the  inner  nodes  in  the  American  form  are  on 
the  umbilical  shoulder  at  all  stages,  the  umbilici  being  deeper  and  the 
volution  thicker  or  stouter  in  proportion  This  species  also  includes 
Grossouvre's  variety  quadratum.  The  saddles  are  more  deeply  undercut 
and  outlines  of  both  lobes  and  saddles  more  complex.  They  are,  however, 
very  closely  representative  species.  Schliiter's  figure  shows  the  impression 
of  a  keel  in  the  impressed  zone  of  the  fragment  of  an  outer  volution,  but 
this  is  probably  either  accidental  or  a  mistake  in  the  figure,  judging  from 
the  description.  The  obvious  excellence  of  Grossou\Te's  work  and  figures 
enables  one  to  see  clearly  the  relations  of  these  forms,  and  he  describes 
them  as  varieties.  We  difter  simply  in  our  estimate  of  their  relative  imjior- 
tance,  he  preferring  to  call  them  varieties,  and  I  to  name  them  as  distinct 
species  in  accordance  with  the  methods  adopted  in  this  and  other  papers. 

Age:  Lower  Senonian  (Santonian). 

Placenticeras  grossouvrei  u.  sp.  Hyatt. 

PlacenticeraK  syrtale  (pars)  Grossouvre,  1893,  Ammonites   Craie   superieure,  pi.  5, 
fig.  32;  p.  16,  fig.  1  (no  others). 

The  French  form  has  no  corresponding'  representative  now  known  ni 
this  covmtry.  The  young,  if  it  be  the  young,  figured  on  pi.  5,  is  costated 
like  the  gerontic  stage  oi  polyopsis  of  Dujardin,  but  it  also  has  a  prominent, 
closely  set  row  of  tubercles  on  either  side  of  the  narrow  concave  venter. 
The  large  fossil  figured  on  pi.  6  has  an  umbilicus  so  very  different  that  if 
it  belonged  to  almost  any  other  genus  one  would  say  at  once  it  could  not 
be  the  same.  In  this  genus,  however,  the  young  are  so  compressed  and 
distinct  that  no   safe   inference   can  be    made  from   figures  alone.     This 


238        PSEUDOCEKATITES  OF  THE  CRETACEOUS. 

specimen  is  certainly  in  the  gerontic  stage,  with  the  median  lateral  row  of 
tnbercles  already  on  the  borders  of  the  venter.  The  ventral  rows  shown 
in  fig.  3  of  pi.  5  have  disappeared  entirely,  and  the  venter  is  smooth  and 
flat  and  very  broad,  the  tubercles  nearly  opposite.  The  inner  row  of  nodes 
begins  to  recede  from  the  line  of  involution  very  early  and  gradually 
approximates  to  the  outer  row.  On  the  last  quarter  these  tubercles  again 
begin  to  apjjroach  the  umbilical  shoulders,  increasing  their  distance  from 
the  outer  line — a  movement  not  ]jaralleled  in  any  American  form  I  have 
as  yet  seen. 

Aye:  Lower  Senonian  (Santonian). 

Placenticeras  iNCisuM  n.  sp.  Hyatt. 

Placentlcefras  syrtale  (pars)  Grossouvre,  1893,  Ammonites   Craie   superieure,  pi.  8, 
fig-.  1  (no  others). 

In  this  form  the  volution  is  described  and  figured  as  compressed  and 
smooth  until  a  late  stage.  The  specimen  is  in  the  jiarephebic  substage  on 
the  first  quarter  of  the  outer  volution;  i.  e.,  the  median  lateral  line  of  tubercles 
is  close  to  the  ventral  line.  The  venter  is,  however,  still  concave,  narrow,  and 
tuberculated.  On  the  second  quarter  the  venter  broadens  to  these  lines  of 
tubercles,  the  ventral  ones  disappear,  the  inner  line  ()f  large  nodes  appears 
first  at  the  center  of  the  lateral  zone.?  and  rapidly  approximates  to  the  outer 
lines,  being  joined  to  them  by  costse.  There  are  only  five  of  these  nodes, 
and  while  the  third  and  fourth  are  nearest  to  the  venter,  the  fifth  is  set 
somewhat  farther  away  inwardly,  thus  nidicating,  as  in  i/rossouvrei,  the 
same  tendency  of  the  nodes  to  return  inwardly  in  extreme  age.  The 
peculiar  broad,  concave  venter  of  the  paragerontic  substage  is  also  akin  to 
the  aspect  of  the  venter  in  an  earlier  substage  in  ffrossouvrei,  but  is  a  great 
exaggeration  of  this  tendency,  and  occurs  after  the  venter  has  become 
convex  in  the  anagerontic  substage,  as  is  shown  on  the  lower  outline  of 
fig.  lb.  These  figures  are  so  fine  that  these  observations  are  made  upon 
their  authority,  and  show  a  great  difi'erence  between  these  and  related 
American  forms. 

Grossouvre's  reference  of  this  variety  to  P.  milleri  of  Haiier  allows 
more  latitude  for  variation  than  is  given  in  this  memoir.  Jlilleri  has  only 
one  row  of  tuVjercles,  and  the  form  of  the  venter  is  distinct. 

Age :   Senonian. 


PLACENTICERATID.E.  239 

Placenticeras  milleri  (Hauer). 

Ammonites  milJeri  Hauer,  1866,  Sitzungsbei'.  K.  Akad.  Wiss.,  Wien,  LlII,  p.  3(14. 
pi.  2. 

This  species  from  Steirmark  is  quite  distinct  from  mw  of  the  French 
forms  described  by  Grossouvre,  but  it  may  be  identical  with  some  of  the 
German  forms  ah-eady  described  having  but  one  row  of  tubercles  in  an 
advanced  stage  of  development.  It  has  smooth  sides,  with  only  one  row  of 
tubercles  on  the  outer  volution,  and  apparently  also  in  the  earlier  stages,  as 
figured  and  described  by  Hauex".  As  stated  by  that  author,  it  is  very  like 
bidorsatus,  except  that  it  has  a  convex  and  moderately  broad  venter.  This 
last  character  also,  as  well  as  the  peciiliar  form  of  the  nodes  on  the  edges 
of  the  venter  and  absence  of  inner  lines  of  tubercles,  separates  it  from 
Grossouvre's  species.     Hauer  had  specimens  from  2  to  3  J  inches  in  diameter. 

Age :  Senonian. 

Placenticeras  schluteri  n.  sp.  Hyatt. 

Ammonites  ayrtali-s  var.  polyopsis  Schliiter,  1872,  Palseontogr.,  Vol.  XXI,  pi.  1-4, 
figs.  1-2. 

This  species  has  ornaments  very  similar  to  those  oi  polyopsis  Dujardin, 
but  these  are  quite  distinct  and  peculiar  in  their  ontogeny.  The  ephebic 
stage  has  two  rows  of  large  lateral  tubercles,  as  well  as  ventral  rows,  and 
according  to  Schliiter's  figures  and  descriptions  the  inner  row  in  the 
anagerontic  substage  recedes  outwardly,  becoming  approximate  to  the 
second  outer  row.  The  venter  at  the  same  time  changes,  becoming  rounded 
and  broader,  but  the  ventral  tubercles  are  still  present.  These  figures  are 
similar  to  the  American  syrtale,  but  differ  in  being  less  involute  and  in  the 
wider  removal  of  the  inner  row  of  tubercles  from  the  umbilical  shoulders 
and  the  elliptical  section  of  the  gerontic  stage.  In  syrtale  this  section  is 
distinctly  subtriangular  and  more  compressed  in  the  same  metagerontic 
substage. 

Age:  Lower  Senonian. 


240  PSEUDOCERATITES  OF  THE  CRETACEOUS. 

Placenticeras  orbignyanum  (Geinitz). 

Ammonites  vihrayeanm  Geinitz,  1843,  Verst.  v.  Kieslin^walde,  PI.  I.  fig.  8. 
Avirnovites  oi'hignyamm  GiQimtz^  1850,  Quadersand.  in  Deiitschl..  pi.  14. 
Avmwnites  orhignyanus  Drescher,  186-S,  Zeitschr.  Deutsch.  geol.  Gesell.,  Vol.  XV, 

%.  8. 
Ammonitea  orhignyanus  Fi'itsch  and  Schlonbach,  1S72,  Ceph.  bohni.  Kreide,  pi.  10, 

figs.  4,  5. 
Ammonites  orhignyanus  Geinitz,  1875,  EDithalgeb.  in  Sachsen,  pi.  36. 
Ptacent.  yritseki  Grossouvre,  1893,  Ammonites  Craie  superieure,  pi.  5,  figs.  1,  2. 

This  species  has  fold-like  costse  and  broad  venters  in  the  young,  as 
figured  by  Fritsch  and  Schlonbach  and  by  Geinitz  in  his  Quadersandstein- 
gebirge.  One  can  not  say  anything  definitely  from  the  figure  given  in  the 
first  publication  under  name  of  vihrayeanus.  The  figure  in  Elbthalgebirge 
also  apj^ears  to  be  the  young  of  this  same  species;  consequently  Drescher's 
figure  of  the  suture  quoted  above  must  also  belong  to  this  species  and 
serves  to  correct  the  conventional  figure  given  in  Quadersandsteingebirge. 
There  are  three  principal  saddles,  as  in  other  species  of  this  genus. 

Grossouvre's  figures  are  excellent  and  give  clear  ideas  of  this  species. 
The  broad,  smooth,  convex  venter  of  what  is  j^robably  the  gerontic  stage, 
and  the  voung,  both  having  costa?  like  the  figures  in  the  Quadersandstein- 
gebirge, appear  to  show  that  the  French  and  German  forms  are  identical. 
The  sutures  as  figured  are  diff'erent,  but  this  may  be  due  to  the  poor 
drafting  of  the  figures  in  the  Quadersandsteingebirge  and  in  the  Zeitschrift 
l)y  Drescher. 

Age:  Lower  Senonian. 

Placenticeras  polyopsis  (Dujardin). 
Ammonites  polyojysis  TyxxisivAin,  1837,  Mem.  8oc.  geol.  France,  No.  2,  pi.  4. 

This  species  has  a  form  similar  to  pseiidorhignyamim,  but  only  in  old 
age,  the  ephebic  stage  being  smooth.  The  flattening  of  the  venter  in  the 
gerontic  stage  is  a  transforaiation  that  may  occur  in  any  species  of  this  and 
other  genera  at  the  same  age  and  can  not  be  considered  to  indicate  specific 
identitv.  The  ornaments  are  altogether  different.  The  tubercles  of  the 
outer  row  are  more  or  less  connected  with  the  inner  row  by  indistinct,  more 
or  less  bifurcated,  costaj,  and  the  inner  row  does  not  change  place  with  age. 
The    ventral    tubercles    are  larger  and    more    widely    separated    than    in 


PLACENTICERATID^E.  241 

schliiferi,  and  all  the  tubercles  and  costse  occur  onlv  in  old  age,  according 
to  the  figures,  Avhereas  in  the  latter  they  are  present  in  adults  as  well  as  in 
the  gerontic  stage. 

Age:  Lower  Senonian. 

Placenticeras  crassatum  n.  sp.  Hyatt. 

Ammfmites  syrtalis  var.  orbignynnm  Schliiter  (pars),  1872,  Palseontogr. ,  Vol.  XXI, 
pi.  14,  figs.  4-7,  fig.  3?  (no  others). 

This  species  differs  from  schliiteri,  being  more  compressed.  The 
recession  outwardly  on  the  inner  row  of  tubercles  does  not  take  place. 
The  inner  row  of  tubercles  disappears  in  what  is  probably  the  anagerontic 
substage,  and  in  this  also  fold-like  costa^  are  develo^jed.  The  venter 
remains  flattened,  the  sides  flat,  and  the  ventral  tubercles  are  still  well 
developed  in  this  substage. 

Affe:  Lower  Senonian. 

Placenticeeas  tamttlicum  (Blanford). 

Avwionites  tamulicus  Blanfonl.  1863,  Mem.  Geol  Surv.  Iiidiii.  Vol.  IV,  p.  118. 
Ammonites  guadalupse,  Stoliczka,  1866,  Pal.  Indica,  Vol.  I,  pi.  47,  and  pi.  48,  tig.  1. 
Placenticet'ds  tanodicuiii  Kossmat,  1895,  Beitr.  Pal.  mid  Geol.  Oesterreich-Uiigarns 
und  des  Orients,  Vol.  IX,  pi.  22,  figs.  1  a-c. 

The  neanic  stage  of  this  Indian  species  is  figured  by  Kt)ssmat,  and 
this,  together  with  the  figures  by  Stoliczka,  shows  that  this  shell  had  a  more 
compressed  form,  flatter  sides,  narrower  ventral  zone,  and  difterent  sutures 
iu  the  adult  and  less  prominent  and  less  distinct  costations  than  the 
gibbous-sided  form,  also  included  in  this  species  by  Stoliczka  in  Paleonto- 
logia  Indica  and  figured,  pi.  47,  fig.  2,  sutures  being  also  given,  fig.  2a. 
There  are  considerable  variations  in  the  shapes  of  the  saddles,  between  the 
last  figure  and  those  of  tamuUcum  {giiadahipce)  on  jjl.  48,  fig  1,  which  can 
hardly  be  accounted  for  by  diff'erences  of  age  in  the  specimens.  It  is  diffi- 
cult of  course  to  say  to  which  of  the  two  forms  the  large  specimen  on 
pi.  47,  fig.  1,  may  belong,  and  any  attempt  to  separate  them  under  diiferent 
names  would  not  be  advisable.  This  last  figure,  183  mm.  in  diameter,  ia 
in  the  gerontic  stage  and  shows  a  second  external  row  of  nodes  of  large 
size  and  the  inner  row  increasing  greatly  in  size  to  blunt  nodes  on  the  last 
part  of  this  volution.  None  of  these  authors  mentions  any  rouuding-off"  of 
MON  XLIV — 08 16 


242  PS-EUDOCEKATITES  OF  THE  CRETACEOUS. 

tliu  venter  in  old  age,  and  apparently  the  venter  retains  its  epheljic  char- 
acters in  this  old  specimen.  I  can  not  join  Kossmat  in  considering  syrtale 
of  Schliiter  as  identical  with  this  species.  The  American  syrtale  shows  old 
age  at  a  smaller  size  than  in  tamnUcum,  and  the  nodes  and  spines  are  much 
larger  and  last  longer,  especially  the  median  lateral  row,  but  it  is  much 
closer  to  this  species  than  to  any  other  European  form  except  schliiteri. 
The  more  compressed  foi'm  of  pi.  48  has  the  external  characters  of  the 
American  lenticulare  as  figured  by  Meek,  but  the  sutures  are  quite  distinct. 
Age :  Lower  Senonian. 

Placenticeras  pseudorbignyanum  n.  sp.  Hyatt. 

Ammo/iitcs  ><yrtal!8  var.  orhignyanus  Schliiter  (pars),  1871,  PaU«ontogr.,  Vol.  XXI, 
pi.  15,  figs.  3-5,  no  others. 

Schliiter's  figure  of  a  typical  example  of  orbiynyanus  is  not  similar  to 
that  of  Fritsch  and  Schloenbach,  nor  to  Geinitz's  species,  nor  does  it  agree 
with  his  var.  orViynyanns  given  on  pi.  14.  It  is  a  very  distinct  shell,  having 
but  one  median  lateral  row  of  tubercles  in  the  neanic  stage.  It  is  otherwise 
smooth  and  with  narrow  ventral  zone. 

Age :  Lower  Senonian. 

I'LACENTICERAS   I   SUBTILISTRIATUM    Jiuibo. 

Placentlccras  .'  .•mbtilistrlatuin,  Jimbo.  1894,  Paliton.  Abhandl.,  new  series.  Vol.  II, 
pt.  3,  pi.  1,  figs.  1,  la. 

This  is  merely  mentioned  here  to  call  attention  to  the  distribution  of 
the  genus.  It  is  figured  as  a  young,  compressed  shell  and  is  certainly  in 
aspect  like  a  species  of  this  genus.  The  figure  has  a  centran  trace  or  keel 
on  the  venter,  although  this  part  is  described  as  being  simply  convex. 

DIPLACMOCERAS"  Hyatt. 

This  genus  resembles  Engonoceras  quite  closely  in  its  involute  com- 
pressed volutions  and  channeled  venter  bordered  by  continuous  ridges,  and 
in  the  tuberculatiou  of  the  sides  it  is  sufficiently  near  to  be  included  in  that 
genus  if  the  sutures  were  unknown.  These  are,  however,  well  known, 
thanks  to  Schliiter's  fine  figures,  and  they  appear  to  be  similar  to  those  of 

"  JiTtXooi,  double;  dKfir),  edge.     Misspelled  Diplacomoceras  in  Zittel's  Text-book,  Ceph.,  p.  585. 


PLACENTICERATID.E.  243 

Placenticeras.  This  genus  therefore  combines  the  external  characters  of 
Engouoceratidse  with  the  sutural  hnes  of  Placenticeratidse,  and  perhaps 
ought  to  be  placed  in  a  separate  family. 

The  young,  however,  are  unknown,  and  it  is  perhaps  better  to  wait 
until  their  development  places  their  affinities  on  a  firmer  basis.  It  is  also 
possible  that  they  may  be  accounted  for  as  members  of  the  Placenticeratidse 
that  were  arrested  in  their  development,  retaining  the  neanic  condition  of 
the  venter  and  lateral  zones  in  their  later  stages,  but  not  arrested  in  their 
sutures,  whicli  approximate  to  those  of  Placenticeras. 

DiPLACMocERAs   BiDORSATUM  (Roemer). 
A?ni)ianites  bidorsaius  ^oemev.  ISil,  Verst.  nord.  Kreidegeb.,  p.  88,  pi.  13,  tig.  5. 

This  species  lias  an  outer  row  of  lateral  tubercles,  according  to 
Roemer's  figures,  with  an  inner  row  of  folds  or  costse  directed  apicad.  The 
outer  row  of  lateral  tubercles  are  elongated  continuations  of  the  costse  and 
are  bent  orad,  forming  crest-like  tubercles  near  and  parallel  to  the  edges  of 
the  venter.  This  last  is  a  concave  zone,  bordered  bv  two  continuous  ridges 
without  tubercles.  The  outer  volution  is  decidedly  compressed,  but  is 
rather  stout  in  proportion  to  its  dorso-ventral  diameter.  This  species  is 
obviously,  unless  both  the  figures  and  description  are  erroneous,  quite 
distinct  from  the  hklorsatum  of  Schliiter,  in  having  stouter  volutions  and 
broader  venter  and  in  the  inner  lines  of  narrow  folds.  There  is,  however, 
considerable  resemblance  between  the  two,  find  it  is  unlucky  that  Roemer 
did  not  figure  the  sutures. 

Age:  Lower  Senonian. 


DiPLACMOCERAS    CANALICULATUM  U.  sp.  Hyatt. 

Ammonifes  j>oly  ops  is  Schliiter,  1867,  Ammoneen  norddeutsch.  Senon.,  pi.  4. 
Ammonites  hidorsatus  Schliiter,  1872,  Pala;ontogr.,  Vol.  XXI,  pi.  1.5,  ligs.  6-8. 

This  species  is  very  peculiar,  having  a  well-defined  gerontic  stage  with 
a  row  of  lateral  tubercles"  set  well  out  near  the  venter  and  becoming- 
nodose  or  prominent.  The  shell  in  the  ephebic  stage  is  smooth  and 
compressed,  the  venter  is  extremely  narrow  and  channeled,  and  there  are 

« These  are  in  no  way  comparable  with  ventral  lines  of  tubercles  as  they  occur  in  Placenticeras, 
being  on  the  sides  and  near,  but  not  on,  the  edges  of  the  venter. 


244        PSEUDOCERATITES  OF  THE  CRETACEOUS. 

smooth  continuous  ridges  on  either  side  that  can  be  compared  with  those  of 
Eugonoceratidff.  The  differences  between  the  shell  figured  by  Schliiter 
and  the  hidorsatuni  of  Roemer  are  so  well  shown  in  the  drawing  given  by 
the  latter  that  there  can  be  but  little  doubt  they  are  different  species.  The 
sutures  are  not  distinct  generically  from  those  of  Placenticeras,  and  would 
place  the  species  in  that  genus  if  the  characters  of  the  shell  were  not  so 
different. 

Locality:  Westphalia. 

A(/e:  Lower  Senonian. 

Incertae  sedis. 

STYRACOCERAS  "  n.  gen.  Hyatt. 

Ammonites  balduri  of  Keyserling,  the  type  and  only  known  species  of 
this  genus,  can  not  be  associated  with  any  s]iecies  known  to  have  same 
number  of  principal  lateral  saddles,  because  the  external  characters  differ 
from  those  of  any  species  known  to  me.  The  resemblances  in  the  sutures 
are  certainly  closer  to  Platylenticeras  heteropleurmn  than  to  any  other  species, 
if  Keyserling's  drawings  and  Neumayr's  observations  are  correct.  The 
suture  has  two  broad  principal  lateral  saddles,  the  first  and  second,  or  else 
these  maj-  be  reckoned,  as  in  others  of  this  group,  as  one  saddle  divided 
into  two  branches.  Until  the  young  are  known,  this  can  not  be  definitely 
decided.     (See  Platylenticeras^ 

Styracoceras  balduri  (Keyserling). 

Aiiiiiionites'baldiiri  Keyserling,  1S46.  Petschora-Land.  pi.  m,  tig.  2. 

The  young,  as  figured  by  Keyserling,  has  a  channel  on  the  venter  in 
the  neanic  stage  after  passing  through  a  substage  with  an  acute  venter. 
This  figure  may  have  been  taken  from  a  partly  crushed  fossil.  So  far  as 
known,  the  replacement  of  an  acute  condition  of  the  venter  by  a  furrow  is 
exceptional  and  requires  more  proof  than  a  single  drawing.  Neumayr 
obtained  the  originals  of  Keyserling's  description  and  studied  them,  but  his 
attention  was  not  apparently  attracted  to  this  fact,  and  he  did  not  break 
down  any  of  the  fossils  to  investigate  the  young.  He  redescribed,  but, 
unluckily,    did  not  have    them  redrawn,   and   did    not   state  whether  the 

1^  2TVpa^,  spike  on  the  inner  end  of  a  spear. 


PLACENTICERATID.E.  245 

smallest  fossil,  about  10  mm.  in  diameter,  was  exactly  represented  in  Key- 
serling's  fig'm'e  which  shows  the  acute  venter.  Neumayr"  does,  however, 
state  clearly  that  the  venter  becomes  furrowed  at  15  mm.  in  diameter,  and 
that  this  furrow  is  succeeded  by  a  stage  with  a  rounded  venter  which  pre- 
ceded the  incoming  of  a  stage  with  a  slightly  convex  venter  and  distinct 
ventro-lateral  angles,  and  that  this  precedes  a  stage  with  distinct  keel  devel- 
oped upon  the  elevated  venter,  and  tubercles  developed  upon  the  costae 
internally  and  at  their  terminations  on  the  ventro-lateral  angles.  Such  an 
extraordinary  succession  of  transformations  is  irreconcilable  with  those  of 
the  ontogeny  of  any  group  known  to  the  author.  The  resemblances  of  the 
sutures  are,  therefore,  not  sufficient  to  place  the  genus  in  the  same  group 
with  Plutylenticeras,  from  which  it  differs  in  every  other  respect. 

Neumayr's  view  of  the  affinities  of  this  genus  for  the  Amaltheidse  is 
not  sustained  by  anything  except  the  general  similarity  of  the  external 
aspect  of  adults,  which  is  probably  due  to  parallelism,  and  the  same  is  true 
of  its  supposed  affinities  for  CarcUoceras.  The  characteristics  of  form  and 
ornamentation  supposed  to  be  so  similar  have  obviously  arisen  from  entirely 
distinct  modes  of  develo^jment,  and  these  genera  are  not  even  as  closely 
related  to  each  other  as  to  Styracoceras. 

Age:  Neocomian. 


aUeber  Amalth.  balduri  Keyserl.  u.  d.  Gattung  Cardioceras.     Neues  Jahrb.  fiir  Min.,  GeoL,  and 
Pal.,  1886,  1,  p.  95. 


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Les  Ammonites  du  Cretace  superieur  de  TAlgerie:  Mem.  Soc.  geol.  France, 

Paleontologie,  Vols.  VI  and  VII,  No.  17.     1896,  1897. 

Pictet,  F.  J.,  and  G.  Campiche.     Description  des  fossiles  du  terrain  Cretace  des 

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PLATES. 


251 


PLATE    I. 


253 


PLATE    I. 

MOJSISOVICSIA,    BUCHICERAS.    ROEMEROCERAS. 

Page. 

Figs.  1-3.  Mojsisoincsia  durfeldi  Steinniann 2.5 

Specimens  from  Pariatambo,  Peru;  Albian?  (after  Steinmann). 

Figs.  4-9.  BucMceras  hilohatum  Hyatt 27 

Figs.  4,  5.  Natural  size. 

6.  Enlarged,  showing  cost^ie  and  aspect  of  center. 

7.  Front  view  of  center  of  fig.  6. 

8.  Suture  from  outer  volution,  part  broken  off  in  fig.  6,  X  3. 

9.  Suture  of  young  X  10  when  the  costje  begin  to  appear. 
Cachiyacu,  Peru;  Upper  Cretaceous;  my  collection. 

Figs.  10-14.  Roemeroceras  nyriaciforme  Hyatt 31 

Fig.  10.  Aged  specimen. 

11.  Suture  of  same. 

12.  Younger  stage  of  another  specimen,  all  natural  size. 

13.  Suture  of  same,  right  side,  X  3. 

14.  Suture  of  same,  left  side,  X  3. 
Cajamarca,  Peru;  Upper  Cretaceous;  my  collection. 

Fig.  1.5.  Roenieroceras  aUenuiitiim  ( Hyatt) 33 

Fig.  15.  Suture,  natural  size.     The  second  lateral  saddle  has,  by  an  oversight  on 
the  author's  part,  been  drawn  too  decidedly  as  trifid.     It  is  really  a  bifid 
base  with  a  prominent  outer  marginal  and  much  like  the  same  saddle  in 
fig.  13. 
Celendin,  Peru;  Upper  Cretaceous;  my  collection. 

254 


U.   S.    GEOLOGICAL  SURVEY 


MONOGRAPH    XLIV      PL.    r 


MOJSISOVICSIA,    BUCHICERAS,    ROEMEROCERA3 


PLATE  II 


255 


PLATE    II. 

ROEMEROCERAS,  PaRATISSOTIA. 

Page. 

Figs.  1-3.  Roemeroceras  gabbi  Hyatt 30 

Figs.  1,  2.  Xatural  size. 

3.  Enlarged  suture.     Coll.  Acad.  Nat.  Sci.  Philadelphia. 
Quebrada  de  Colpamayo,  Peru;  Upper  Cretaceous;  all  after  Gabb. 

Figs.  4-6.  Roeineroceras  suhjilannm  Hyatt 34 

Figs.  4,  5.  Natural  size. 
6.  Suture,  X  2. 
Cajamarca,  Peru;  Upper  Cretaceous;  my  collection. 

Figs.  7-11.  Paratissolia  serrata  (Hyatt)  51 

Figs.  7,  8.  Natural  size. 

9.  Fig.  8  enlarged. 

10.  Center  of  fig.  8  enlarged  to  show  section  of  young  and  solid  keel. 

11.  Lateral  and  dorsal  suture  of  fig.  7  above  the  break. 
Cachiyacu,  Peru;  Upper  Cretaceous  (Senonian?);  my  collection. 

256 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH    XLIV       PL.    II 


R0EMER0CERA5,    PARATISSOTIA. 


PLATE   III. 


MON    XLIV — (»;j 17  ,  257 


PLATE   ITT. 
Paratissotia,  Sphenodiscus. 

Page. 

Figs.  1-6.  Puralissotia  regularin  II yalt 53 

Figs.  1-3.  Natural  size.  The  venter  is  restored  in  fig.  1,  and  in  flg.  3  the  hollov 
keel  is  restored  except  in  lowest  volution  of  section,  which  is  as  seen 
in  fig  4. 

4.  F.nlarged  view  of  section  of  venter  of  lower  whorl  of  fig.  3,  showing 

hollow  keel  on  its  first  appearance. 

5.  Suture  of  first  quarter  of  outer  volution  of  fig.  2;  dor.<al  saddles  merely 

indicated. 

6.  Much  abraded  sutures  of  last  quarter  of  same,  to  show  tlie  number  and 

general  proportions  of  the  curves;  the  \'entral  lolie  is  more  deei)ly  worn 
than  the  lateral. 
Cachiyacu,  Peru;  Upper  Cretaceous;  my  collection. 

Figs.  7-1.5.  Splienodiseus  pleurisepla  ( Coni-ad ) 59 

Figs.  7-9.  Natural  size.     Rio  Pecos, (?)   Tex.;    Upper  Cretaceous;   Coll.  Columbia 
University,  New  York,  No.  10881. 
10.  Enlarged  center  of  fig.  9.     The  sutures  in  this  were  not  so  clearly  seen  as 
to  make  the  observation  in  this  and  fig.  12  entirely  reliable. 
11,12.  Enlarged  outlines  of  young  of  fig.  9. 

13.  Older   specimen  than  figs.  7-12,  showing  the  rounding  of  the  venter. 

Xear  Eagle   Pass,  Tex.;  U.  S.  Nat.  Mus.  Coll.  No.  1914.5a. 

14.  Loc.  same,  coll.  same.  No.  1914.5b.     Same  age  as  figs.  7  and  8,  l)ut  showing 

more  acute  venter  and  more  prominent  tubercles;  tliis  variation  has 
been  slightly  increased  by  compression. 
1-5.  Suture  X  21  of  specimen    represented  by  PI.  V,  tig.   3.     Kio   Pecos,  (?) 
Tex.;  Coll.  Columbia  University,  No.  10881c. 
All  im  this  plate  are  casts. 

258 


U     S.   GEOLOGICAL  SURVE 


Monograph  xliv     pl.  iil 


PARATISSOTIA,    bPHENODlSCUS 


PLATE   IV. 


259 


PLATE    IV. 

Sphenodiscus  pleurisepta  (Conrad). 

(Page  59.) 
Figs.  1,  2.     Loc.  No.  1473,  near  Eagle  Pass,  Tex.;  Upper  C'retaeeous:  Coll.  U.  S.  Geol.  Survey. 
260 


b-   S.    GEOLOGIUAL    SURVEY 


ONOGRAPH   XLIV       PL.    IV 


SPHENODISCUS. 


PLATE    V, 


261 


PLATE    V. 

Sphenodiscus. 

Figs.  1-3.  Sphenodiiicnx plenrlxepta  (Conrail)    59 

Figs.  1,  2.  Fig.  2  is  i-estored  in  the  lower  part.     The  venter,  where  it  is  oovered  l)y 
the  shell,  is  slightly  more  acute  than  is  shown  in  the  drawing.     Near 
Eagle  Pass,  Tex.;  Upper  Cretaceous.     Ooll.  U.  S.  Geol.  Survey. 
3.  Ventral  view  of  same  fossil  as  figured  in   PI.  Ill,  fig.  1.5.     Coll.  Colum- 
bia University,  Xo.  lOSSlc. 

Fig.        4.  Splifnodiscuf:  stantoni  Hyatt 70 

Fig.  4.  The  sutures  do  not  show  very  well  in  this,  and  an  enlarged  view  of  the 
first  six  saddles  is  given  on  PI.  VI,  fig.  5.  Same  locality,  age,  and  col- 
lection as  figs.  1-2. 

262 


U     S.   GEOLOGICAL    SURVEY 


MONOGRAPH  XLIV      PL.   V 


i 


SPHENODISCUS. 


PLATE    VI. 


263 


PLATE    VI. 
Sphenodiscus. 

Page. 

Figs.  1,  2.   SjjheiioilinniK  lahatiix  ( Tuoniey ) 'W 

t^hows  the  abnormally  shortened  living  chamber  ami  flaring  al^nornuil  aperture  and 
partly  absorbed  sutures.  Lander's  mill,  Tippah  County,  ^liss. ;  Kipley  group; 
Coll.  U.  S.  Nat.  Mus.,  No.  20577. 

Figs.  3,  4.  SpIu-nodiyciiK  hi'i-rhcri  Hyatt 78 

Birmingham,  N.  J.;  Lower  or  Middle  Oreensand  marls,  Upper  Cretaceous;  Coll. 
Yale  XTniv.  ilus.,  No.  200. 

Fig.        ■").  Splienodixcnn  xtatiloiii  Hyatt - 70 

Sutuiv  from  specimen  figured  on  PI.  V,  lig.  4,  showing  the  jirincipal  saddles  and 
lobes,  Xo. 

Fig.        (i.  Sjiliiniidincus pleurhepid  (Conrad) i'>9 

Buncombe  Hil-ls,  Pontotoc  County,  Miss.;  Ripley  group,  Upper  Cretaceous;  Coll. 
Frederick  Braun. 
■2fi4 


U.    S.   GEOLOGICAL   SURVEY 


Monograph  xliv     pl.  vi 


SPHENODISCUS. 


PLATE    A^I. 


265 


PLATE   VII. 

Sphenodiscus  lobatus  (Tuoiiiey). 

( Page  66. ) 

Figs.  1,  2.  Pontotuc  Cuunty,  iliss. ;  Ripley  group,   Ui>ijer  Cretaceou.«;  foil.  V.  S.  Nat.  Mils., 
Xo.  2403,  I  natural  size. 

266 


PLATE    VIII. 


267 


PLATE     V  I  n . 

Sphenodiscus. 

Page. 

Fi(;s.  1 ,  2.  .SphcitodiKCUs  lenticularis  (Owen  ) 71 

Fig.    1.  Young  of  supposed  typical  forni,  natural  size.     See  also  PI.  IX. 
2.  Suture  of  same  X  Gl. 
Moreau  River,?  Dakota;  Fox  Plills  group;  Coll.  T'.  S.  Nat.  Mus.,  Xo.  7754. 

Figs.  3-7.  Sphenodhcua  lenticularix  \;\r.  splendeiis  Hyatt 75 

Figs.  3,  4.  Views  of  fragment.'?  showing  lateral  sutures  ami  internal,  loose  younger 
volution,  natural  size. 
5.  Dorsal  suture  of  one  side  of  about  same  age  as  the  one  painted  in  on  fig. 

3,  natural  size. 
t>.  Antisiphonal  lobe  of  fig.  5,  much  enlarged. 

7.  First  three  saddles  and  siphonal  saildle  to  show  outlines  on  the  next 
inner  volution  to  that  of  fig.  3,  natural  size. 
South  Dakota;  Fox  Hills  group;  my  collection. 

268 


U.   S.   GEOLOGICAL    SURVEY 


MONOGRAPH    XLIV      PL. 


^nv|v. 


SPHENOOISCUS. 


PLATE   IX. 


269 


PLATE    IX. 

Sphenodiscus. 

Page. 

Fic;s.  1-6.  Sphe.nodisvHx  Untindqrix  (Owen ) 71 

Fig.    1.  Suture  of  parancpionic  .substage,  X  -h. 

2.  Details  of  fiphunele,  showing  what  seemed  to  be  a  collar  above  and  a  jiro- 

limgeii  funnel  reaching  frf-in  the  septum  to  the  opening  of  the  collar. 

3.  Sutures  of  the  neanic  stage,  showing  the  division  of  the  first  primitive  lat- 

eral into  three  saddles,  first,  second,  and  third  of  the  later  stages,  and 
the  mode  of  increase  of  the  so-calleil  auxiliary  saddles  and  lobes  on  the 
line  of  involution,  X  5. 

4.  Section  of  the  two  j-oungest  volutions  obser\ed,  X  -^  4. 

5.  Lateral  suture  of  later  but  not  fully  adult  stage,  X  6. 

6.  Dorsal  suture  of  same  age,  X  S. 

Rock  Creek,  Wyoming;  Fox  Hills  group;  Cull.  Vale  Ciiiversity,  Xo.  1697. 

Fi(is.  7-9.  SphenodisrtiK  loitifii/arii!  var.  missisHppiensis  Hyatt 77 

Fig.    7.  Lateral  suture,  natural  size. 

S.  Dor,«al  suture  of  same  age,  but  one-fifth  over  the  natural  size;  aclual  meas- 
urement is  48  mm.  instead  of  60  mm.,  the  length  of  the  figure. 
9.  Lateral  suture,  natural  size,  from  specimen  in  Coll.  Acad.  Xat.  Sri.  Phila- 
delphia. 
Three  miles  northeast  of  Ripley,  Miss.;  Ripley  group;  Coll.   I'.  S.  Xat.   .Mus., 
No.  2086.Sc. 

Fig.  10.  SjilHiiitilitnis  beechcri  Hyatt 78 

Suture,  natural  size.     Fox  Hills  grou]>;  Coll.  Mus.  Conip,  Zool.,  Cambridge. 

Flos.  1  l-lo.  Sphenodiscus  lobalns  (Tuomey) ,         66 

Fig.  11.  Right  side. 

12.   First  three  saddles  of  left  side  at  same  age,  natural  size, 
l.'i.   First  three  saddles  of  left  side  of  the  youngest  suture  shown  on  I'l.  \'II, 
fig.  1,  natural  size,  for  comparison  with  fig.  12. 
Buncombe  Hills,  Pontotoc  County,  Miss.;  Ripley  group;  Coll.  Frederick  I5raun, 
Brooklyn,  X.  Y. 

270 


U.   S.   GEOLOGICAL   SURVEY 


MONOGRAPH    XLIV       PL.    U 


SPHENODI5CUS, 


PLATE   X. 


271 


PLATE    X. 

COILOPOCERAS,  SpHENODISCUS. 

Page. 

Fiiis.  1  —J.   ('oilopocL'ras  iiorimexirdnuin  Hyatt 94 

Figs.    1-3.  Natural  size,  showing  Imllow  keel,  etc. 

4.  One  entire  lateral  suture  and  parts  of  two  otliers,  x  ^-     The  terniinaticms 
of  the  saddles  were  more  or  less  pointed  depressions  in  the  east  and, 
were  not  at  lirst  observed. 
Near  Carthage,  X.  Mex.;  my  collection. 

Fu;s.  .5-21.   Co'dopoceras  eolletl  Hyatt 91 

Figs.    .5.  0.  Natural  size,  section  partly  restored;  see  also  PI.  XI,  fig.  1. 

7.  Lateral  suture  same  as  in  side  view,  X  -■ 

8.  The  dorsal  suture  of  same  age,  but  a  suture  or  two  later. 

9.  Youngest  suture  shown  in  fig.  .5,  X  -,  showing  the  markeil  changes  that 

occur  on  this  volution. 

10.  First  to  thinl  suture  of  nejiionic  stage,  X  '-0. 

11a.  An  entire  suture  of  latter  ])art  of  first  volution,  X  20. 

11.  Two  entire  sutures  of  fir.st  quarter  of  second  volution,  X  20. 

12.  Entire  suture  of  fourth  quarter  of  fourth  volution.  X  8,  when  the  sutures 

are  beginning  to  show  sul)division. 

13.  The  protocoiich  and  part  of  the  first  volution.  X  --.  same  age  as  fig.  14. 

14.  More  enlarged  side  view  of  the  same. 

15.  16.  An  older  stage  of  the  same  shows  less  of  the  protocomh  and  more 

suture.s. 
17,  18.  A  still  oilier  stage,  showing  the  decreasing  transverse  diameter  of  the 
volutian  in  the  goniatitic  stage,  and  the  fir.-^t  constriction  or  mark  of 
a  nepionic  aperture. 
19,  20.  An  older  stage  of  same,  center  of  fig.  (i,  and  al.-'O  of  tig.  1,  I'l.  XI. 
21.  Shows  the  hyponomic  sinus  of  constriction  or  permanent  aperture  given 
in  figs.  18  and  19.     The  normal  rate  of  growth  and  increase  in  diameters 
of  volution  has  begun  in  this  nepionic  substage. 
Xear  Carthage,  X.  Mex.;  my  collection. 
Fig.  22.   [Suture  of  Sphenodiscus  introduced  for  comparison. — T.  \V.  S.] 
272 


U.    S,    GEOLOGICAL  SURVEY 


MONOGRAPH    XLIV       PL.    X 


COILOPOCERAS,   SH  PENOD  ISCUS. 


PLATE    XI. 


MOX   XLIV— 03 18  273 


PLATE   XI. 

C0II.OPOCERAS,  EULOPHOCERAS,  MeTOICOCERAS. 

Page. 

Fk;.  1.   Coilopoferas  colleli  Hyatt ^^ 

Section  same  as  PI.  X,  fig.  (>,  enlarged. 

Fifis.  2-6a.  EHlophocema  nataleme  Hyatt 86 

Fig.    2.  Side  taken  before  specimen  was  ground  to  show  section. 

3.  Section  somewliat  more  than  natural  size,  and  somewhat  restored,  shows 

the  umbilicus  on  the  right  completely  filled  by  the  shell  layer.s.  This 
filling  occurs  in  the  adolescent  stage,  inclosing  the  dark  spots  on  Ijoth 
sides  of  the  center,  which  indicate  that  the  shell  did  not  fill  the  umbilici 
at  an  earlier  stage. 

4.  Enlarged  view  of  center  restored. 

0, 6.  Shows  keel  to  have  been  solid  at  this  age. 

6a.  Enlarged  drawing  of  hollow  keel  of  venter  connected  by  a  dcitte<l  line. 
Natal,  South  Africa;  Cretaceous;  Yale  IMuseum. 

Figs.  7-24.   Metmcoceras  svallmi  (Shumard ) - 118 

Fig.    7.  Protoconch    and    part   of   nepionic   vohitiun,   X  56-f ,  actual   transverse 
diameter  3/10  mm. 

8.  Side  view  of  same,  showing  the  abrupt  bend  in  the  protoconch  >)efore  tht- 

nepionic  tube  began  to  be  formed,  and  the  first  two  sutures. 

9.  Optical  section  of  same  along  dotted  line  in  fig.  .S  ami  from  frcmt  <>i  view 

shown  by  the  arrow. 

10.  Front  view  of  the  specimen  before  removal  of  the  outer  volution,  X  36. 

11.  Enlarged  view  of  the  ciecum  and  fir.st  section  of  sipliuncle,  showing  also 

the  ventral  lobe  divided  by  a  siphonal  saddle. 
12, 13.  Neanic  stage,  showing  the  aspidoceran-like  form  and  tubercles,  X  6. 
14, 1.5.  A  little   older  stage  with  living  chamber   complete  at  the  umliilical 

shoulder,  over  1/2  volution  in  length,  X  6.     Back  of  this  shows  rormded 

venter  of  the  neanic  stage  just  becoming  divided  by  the  incoming  of  two 

rows  of  tubercles. 
16, 17.  Early  ephebic  substage. 

18.  Sutures  of  fig.  12  about  fir.'^t  quarter  of  fourth  volution,  X  12. 

19.  Suture  of  second  quarter  of  same  volution. 

20.  Suture  of  probably  fourth  quarter  of  same  volution. 

21.  Dorsal  suture  of  the  second  volution,  X  12. 

22.  Dorsal  suture  of  what  was  considered  to  be  the  last  oi  fifth  or  part  of  sixth 

volution,  X  12. 

23.  Dorsal  suture  later  in  age  than  fig.  22,  X  12,  of  same  age  as  suture  PI.  XIII, 

fig.  1. 

24.  Lateral  suture  of  fig.  16  enlarged  3  diameters.     The  ventral  lobe  has  been 

distorted  by  setting  the  siphonal  saddle  at  an  eccentric  angle. 
Texas;  Colorado  epoch;  my  collection. 
See  PI.  XIII  for  other  figures  of  this  species. 

274 


U.   S.   GEOLOGICAL    SURVEV 


Monograph  xliv     pl. 


.-LJV' 


-^^0' 


G 

V 


,-^o~- 


I  6" 


COILOPOCERAS.    EU  LOPHOCERAS,    METOICOCERAS 


PLATE    XII. 


275 


PLATE    XII. 

COILOPOCEEAS,  ACONECERAS,  SpHENODISCUS. 

Page. 

Figs  1-3    CoUopoceran  springrri  Hyatt 96 

Fig.    1.  Suture  of  right  side  of  shell. 

2.  Suture  of  left  side. 

3.  Antisiphonal  lobe  and  first  dorsal  saddle.     Lower  part  of  lobe  below  dotted 

line  and  right  side  is  restored;  the  point,  however,  was  seen  to  be  bifid. 
All  natural  size. 

Eit  du  Plain,  Colfax  County,  N.  Mex.;  Colorado  ei)och,  Upper  Cretaeeous;  C'oll. 
Mus.  Comp.  Zool. 

Figs  4-6    Aconeceras  nisum  (A' Orbigny) 100 

Figs.  4,  .5.  Natural  size  (after  d'Orbigny's  figures). 

6.  Sutures  enlarged,  showing  similarity  to  phylloceran  outlines. 

Fig.  7    CoUopoceras  r/rossouirei  Hyatt 1 00 

Figure  of  sup-posed  Sj/henodismx  reqtiicnicinus  d'Orh.,  showing  coilopoceran  suture. 
(After  Grossouvre. ) 

Fig  8.  Sphenodiscus  konincki  Hyatt .S2 

J'ig.    8.  Suture  natural  size.     Part  of  one  suture  is  shown  and  this  is  continued  by 
the  auxiliaries  of  the  next  suture  below. 
Near  Maestricht;  Senonian;  DeKoninck  Coll.  Mus.  Coiuj).  Zool.,  Candiridge. 

276 


U.  S.   GEOLOGICAL   SURVEY 


MONOGRAPH    XLIV      PL.    XII 


COILOPOCERAS,    ACONECERAS.   S  P  H  E  NOD  ISC  US. 


PLATE    XIII. 


277 


PLATE    XIII. 

Metoicxx'era.s. 

Pa  28. 

Fic;s.  1-2.   Metoiriireriis  stirallnii  (Shuniard) , 118 

Fig.  1.  Same  a.M  PI.  XI,  figs.  20-21!.     First  tliree  saddles  and  two  lobes  of  lateral 
suture,  X   12,   to  show  mode  of  division  of   saddles  and  their  distinct 
marginals  at  this  late  neanic  substage. 
2.  Gravson  County,  Tex;  Coll.  D.  S.  :\Iartin. 

Figs.  3-5.  Metoicoceras  u-hilti  Hyatt 122 

Fig.  3.   Shows  shell  on  part  of  outer  volutiim  an<l   bow  little  this  differs  from  the 
cast. 

4.  Shows  this  also  as  well  as  the  rounding  of  the  living  cliamlier  on  the  venter 

in  old  age.     See  aLso  younger  suture  from  oppo.site  or  left  side:  I'l.  XIV, 
tig.  10. 

5.  Last  suture  of  auotlier  specimen  nf  about  the  same  size  as  tig.  4. 
Upper  Kanab  Valley,  Utah;  Coll.  U.S.Nat.  Miis. 

278 


U.   S.    GEOLOGICAL   SURVEY 


MONOGHAPH    XLIV       PL.    XIII 


METOICOCERAS. 


PLATE    XIV 


27£ 


PLATE    XIV. 
Metoicoceras,  Vascocekas. 

Page 

Fuis.  1-10.  ifiluiroceras  whitei  Hyatt 122 

Fig.s.    1,2.  Exterior,  natural  size,  .'^bowing  living  chamber  nearly  three-fourths  of 
a  volution  in  length,  complete  to  its  inner  border. 

3.  Lateral  suture  of  the  last  septum,  X  3. 

Ehn  Fork,  Horton's  mill,  Dallas  County,  Tex.;  Colorado  epoch. 

4,  5.  Specimen  somewhat  older  than  fig.  1,  natural  size. 
Probably  from  Texas;  my  collection. 

6.  Lateral    suture,    X    3.      Living    chamber,    probably  nearly  complete,  is 

one-half  of  a  volution  in  length. 

7,  8.  Type  of  species,  natural  size. 

9.  Suture,  natural  size,  somewhat  older  than  fig.  4,  whole  diameter  about  56 
mm. 
Elm  Fork,  Horton's  mill,  Dallas'  County,  Tex. 

10.  Lateral  suture,  left  side  of  fig.  4,  PI.  XIII,  taken  from  halfway  between 
the  base  of  the  living  chamber  and  the  opening  of  the  same. 

Figs.  11-14.  Metoicoceras  acceleratum  Hyatt 127 

Figs.  11-13.  Specimen  in  which  the  living  chamber  is  complete  and  over  three- 
fourths  of  a  volution  in  length,  natural  size. 
14.  Part  of  suture  visible  at  base  of  living  cham))er  on  the  opposite  side  to 
that  figured,  X  4. 
Ehn  Fork,  Horton's  mill,  Dallas  Comity,  Tex. 

Fk;.    ^S.  Metoicoceras  ivhitel  Hyatt 122 

Dorsal  suture,  natural  size. 

Elm  Fork,  Horton's  mill,  Dallas  County,  Tex. 

Fiii.     1(5.    Vdscoceras  hariti  (Hyatt) 103 

Suture,  natural  size. 

280 


U.    S.    GEOLOGICAL    SURVEY 


MONOGRAPH     ^LIV       PL.    XIV 


METOICOCERAS.   VASCOCERAS. 


PLATE   XV. 


281 


PLATE    XV. 

Metoicoceeas.  Heinzia. 

Page. 
FiG.s.  1^.  Meioivocems  swallon  (Shumard) 118 

Figs.     1,  2.  The  imperfect  and  crushed  base  of  living  chamber  restored  in  fig.  2. 

3,  4.  Right  and  left  sutures  of  fig.  1,  of  same  age,  showing  differences  in 
number  and  outlines  of  auxiliaries.     All  natural  size. 
Texas;  Colorado  epoch;  Coll.  Amer.  Mus.  Nat.  Hist.,  New  York. 

Figs.  5-8.  Metoicoceratt  fillilidxum  Hyatt 121 

Figs.    5,  6.  Natural  size. 

7,  8.  Suture  of  right  and  left  sides,  respectively,  as  seen  when  lookinj;  at  the 
specimen  fig.  5,  natural  size. 
Texas;  Coll.  Amer.  Mus.  Nat.  Hist.,  New  York. 
Figs.  y-U.   M('toicticer(i>i  bnidbense  Hyati  ". 
Figs.  9,  10.  Natural  size. 

11.  Suture  of  left  side  of  the  second  quarter  of  outer  volution,  X  2J.     The 
living  chamber  extended  from  the  crack  in  the  specimen,  fig.   10, 
for  the  remaining  one-half  volution,  and  was  mo.st  ]irohably  nearly 
complete. 
Upper  Kanab  Valley,  Utah;  Colorado  epoch;  Coll.  I^.  S.  Nat.  Mus. 

Figs.  12-18.  Heinzia  matura  Hyatt -  -  - 1S2 

Fig.  12.  Entire  specimen,  right  side. 

13.  Same  separated  and  center  excavated,  left  side. 

14.  Front  view  of  same,  center  one-half  restored. 

15.  Ventral  view  of  fig.  12. 

16.  Suture  at  place  marked  by  arrow  in  fig.  13,  X  7,  actual  length  3  mm. 

17.  Dorsal  suture,  X  8,  of  second  cjuarter  of  outer  volution  of  fig.  12,  one-half 

actual  diameter  2  mm. 

18.  Suture  of  right  side  fourth  quarter  of  outer  volution  <>i  fig.  12,  X  3. 
All  natural  size  excejjt  figs.  16,  17,  and  18. 

Escragnolles,  France;  Barremian;  Coll.  Mus.  Comp.  Zool.,  Cambridge. 

Figs.  19,  20.  Heliiziapi-tirincialis  (d'Orbigny) 131 

Fig.  19.  Dorsal  suture  next  to  outer  volution  across  the  umbilicus  and  opposite 
termination  of  outer  volution,  X  9,  one-half  actual  diameter  1.5  mm. 
Of  same  type,  but  more  immature  at  the  same  age  than  in  Heinzia 
matura. 
20.  Natural  size. 
Locality  and  collection  same. 


"  No  description  of  this  species  was  found  in  the  manuscript. — T.  W.  S. 
282 


U.   S.   GEOLOGICAL    SURVEr 


MONOGRAPH    XLIV       PL.     XV 


METOICOCERAS,    HEINZiA. 


PLATE   XVI. 


283 


PLATE    XVI. 
Heinzia,  Knemicera.s. 

Page. 

Fins.  1-3.  Heimia  prorinciaVis  (d'Orbigny) 1.31 

Figs.    1, 2.  Same  as  PI.  XV,  fig.  20,  broken  to  shpw  young,  X  3. 

3.  Lateral  suture  of  the  second  quarter  of  outer  volution  of   PI.  XV,   fig. 
20,  X  4. 
Escragnolles,  France;  Barremian;  Coll.  Mus.  Comp.  Zool.,  Cambridge. 

Figs.  4-8.  Knemiceras  syriacmn  (von  Buch) 146 

Fig.     4.  Natural  size,  showing  length  of  living  chamber,   over  one-fourth  of   a 
volution.     Coll.  Mus.  Comp.  Zool.,  Cambridge. 

5.  Lateral  suture,  X  -\- 

6.  Uncompressed  typical  fossil.     Coll.  Yale  JIus. 

7.  Part  of  suture  of  right  side,  X  2A,  to  contrast  with  next  figure. 

8.  Suture  of  left  side,  X  3.     Outlines  perfectly  preserved. 
Mount  Lebanon,  Syria;  Cenomanian. 

Figs.  9-10.  Knerniceras  compressuni  Hyatt.     Natural  size 149 

Locality,  same  as  last;  Coll.  Mus.  Comp.  Zool.,  Cambridge. 

Figs.  11-14.  Knemkerax  compressum  var.  subcomjjresfmm  Hyatt 150 

Fig.    11.  Specimen  in  collection  of  Columbia  University. 

12.  Section  showing  transition  from  a  rounded  young  to  the  flat  and  then  con- 
cave venters  of  the  succeeding  stages,  X  2,  from  specimen  in  Mus.  Comp. 
Zool.,  Cambridge. 
13a.  Enlarged  view  of  centei . 
13b.  Enlarged  view  of  protoconch  and  first  volution  with  first  and  second 

sutures. 
14.  One  of  Conrad's  specimens,  natural  size.     Suture  abraded.     Coll.   Yale 
Mus. 
Locality,  same  as  last. 

Figs.  1.5-18.  Knemiceras  comprensnm  Hyatt 149 

Figs.  15, 16.  Type  of  species.     Sutures  abraded. 

17.  Suture  from  line  of  involution  to  first  lateral  lobe  at  breadth  of  54  mm.  on 

left  side. 

18.  Suture  on  right  side  to  third  lateral  saddle  at  breadth  of  63  mm. 
Locality,  same  as  last. 

Fig.  19.  Knemiceras  comp ressniii  yar.  subcompressum  Ptyatt 150 

Ventral  view,  natural  size,  of  specimen  in  collection  of  Columbia  L^niversity.     For 
sutures  see  fig.  11. 
Locality,  same  as  last. 
284 


S.    GEOLOGICAL    SUHVE 


MONOGRAPH    XLrV       PL.    XVI 


HEINZIA.    KNEMICERAS 


PLATE  XVII. 


285 


PLATE     XVII. 

SUBPULCHEIXIA,  NiCKLEMA,  PuUHKI>LIA,   KnIEMICERAS,  PrOTENGONOCEKAS. 

Page. 

Fins.  1-5.  Subpulehellia  castellanensis  Hyatt 140 

Figs.    1,  2.  With  shell  complete  on  side  of  fig.  1. 

3,  4.  Same  fossil,  shell  partly  taken  i.iff.     Right  side  of  fig.  3  shows  length  of 

living  chamber  about  one-half  of  last  volution. 
'  5.  Lateral  suture  of  fig.  3,  X  3. 
All  natural  size  except  fig.  5. 
Castellanes,  France;  Neocomian;  Coll.  Mus.  Comp.  Zool.,  Cambridge. 

Figs.  ti-S.  Nicklesia  dumasiana  (d'Orbigny) 139 

Figs.    6,  7.   Natural  size. 

IS.  Lateral  suture,  X  3. 
Locality  and  collection  same  as  last. 

Figs.  9-12.  Pnlchellki  compressissima  (d'Orbigny ) 142 

Figs.    9-11.  Natural  size. 

12.  Suture  after  Nicklcs,  Pal.  sud-est  de  I'Espagne,  pi.  3,  fig.  11),  X  o. 
Locality  and  collection  the  same. 

Figs.  \'A-\o.  Knemiceras  attenmilum  (  Hyatt  l 151 

Figs.  13,  14.  Natural  size;  shows  living  chamber  nearly  three-fourths  of  a  volution. 
15.  Suture,  X  2.  • 
Celendin,  Peru;  Cenomanian? 

Figs.  16v-20.   Protengonoceras  ydbhi  ( Bohm) 1.53 

Fig.    16.  Shows  living  chamber  to  have  one-half  a  volutimi  in  length.      .Shell  is 
preserved  on  the  living  chamber. 

17.  Section  shows  the  concave  venter  witli  lateral  ridges  at  an  early  stage. 

18.  Ventral  view  of  same. 

19.  Septum  of  same,  X  2. 

All  natural  size  except  the  last,  and  all   in  Coll.  Mus.  Comp.   Zool., 
Cambridge. 

20.  Specimen  in  Coll.  .\cad.  Nat.  Sci.  Phila.     Showing  living  chamber  one-half 

of  a  volution,  part  of  aperture  on  right  side,  and  old-age  folds. 
.\rivechi,  Sonora,  Mexico. 

286 


U.    S.    GEOLOGCCAL    SURVEY 


MONOGRAPH    XLIV       PL.    XVII 


SUBPULCHELLIA     NICKLESIA     PULCHELLIA,    KNEMICERAS,    PROT  EN  GON  OC  E  R  AS. 


PLATE  XVIII. 


2S7 


PLATE    XVIII. 
Knemiceras,  Engonoceras,  Protengonoceras. 

Page 

Figs.  1-3.  Knemiceras  gabbi  Hyatt 1.52 

Figs.  1,  2.  Natural  size.     (After  Gabb.) 

3.  Lateral  suture  enlarged.     (After  Gabb.) 
Quebrada  de  Huari,  Peru;  Cenomanian? 

Figs.  4,  .5.  Engonoceras  hrlriderense  ( Cragin ) 158 

Figs.  4,  5.  Lateral  and  ventral  views. 
Belvidere,  Kaiis. ;  Washita  epoch;  Coll.  Cragin,  Colorado  College. 

Figs.  6-9.   Proienfjonocera.t planum  Hyatt 15fi 

Figs.  6,  7.  Lateral  and  ventral  views.  X  2. 

8.  Lateral  suture,  X  2;  the  auxiliary  sadrlles  Nos.  8  to  10  shouM  be  a  trifle 

broader. 

9.  Dorsal  suture  of  the  same  age,  X  2. 
Texas,  my  collection. 

288 


U.  s.  gEOloG'cal  survey 


Monograph   xLrv     pl.  xvill 


KNEMICERAS,    ENGONOCERAS.    PROTENGONOCERAS. 


PLATE   XIX. 


MON  XLlv— 03 19  289 


PLATE   XIX. 
Engonoceras. 

Page. 

Ficis.  l-tl.  Kmjijnucerds  udileni  (Cragin) 159 

Figs.  1,2.  Type  specimen  from  near  Lindsborg,  Kans.,  natural  size. 
3.  Lateral  suture  of  same,  slightly  enlarged. 

4,5.  Specimen  from  McPherson  County,  Kans.     Natural  size,  showing  living 
chamber  proliably  almost  complete  along  the  umbilical  shoulder  and 
about  one-half  of  a  volution  in  length.     The  crease  on  the  side  of  the 
venter  of  fig.  5  is  an  accident  due  to  conijiression.     Coll.  U.  S.  Nat. 
Mus. 
R.  Lateral  suture  of  opposite  or  left  side,  X  2i.     The  curvature  is  somewhat 
less  than  it  is  on  the  specimen. 
Kiowa  shales,  Comanche  series,  Lower  Cretaceous;  my  collection. 

Flos.  7-14.  Engonoceras  serpendnum  (Cragin ) 162 

Figs.  7,  S.  Natural  size,  living  chamber  one-half  of  a  volution  probably  nearly  com- 
plete on  umbilical  shoulder.     The  venter  of  inner  volution  of  fig.  8  ia 
decidedly  concave. 
9.  Lateral  suture,  X  2. 

10.  Part  of  sutures  of  young  fragment,  X  2.     This  specinicn  is  fmiu  near  Deni- 

son,  Tex. 

11.  V'ariety  with  broad  ends  tcj  the  cost;e  and  crowded  peculiar  suture.s. 

12.  Lateral  sutures,  X  2. 

13.  Ventral  view  of  cast,  with  similar  costfe. 

14.  Suture  of  same  more  like  tlio.se  of  fig.  9.     This  is  not  due  tn  difference  of 

age.     The  last  5  and  half  of  sixth  saddle  arc  dorsal. 
Four  and  one-half  miles  northea.st  of  Gainesville,  Tex.,  Deni.son;  Washita  epoch; 
Coll.  U.  S.  Geol.  Survey. 

Fi(is.  15-17.   Engonoceran  rclurduni  Hyatt « IHO 

Fig.  15.  Natural  size,  showing  the  late  age  at  whii-h  the  venter  remains  angulated, 
flat,  and  without  tubercles.  The  rounded  venter  of  the  older  stage  is  in 
part  due  to  abrasion. 

16.  Shows  what  was  seen  of  the  lateral  sutures. 

17.  Dorsal  suture  of  same  age  as  oldest  suture  on  fig.  16. 

Near  Pottsboro,  Tex.;  Cpper  Comanche  (Grayson).  Washita  ejioch;  Coll.  U.  .^. 
(tcoI.  Survey. 

"The  specimen  here  figured  as  E.  relarilum  is  describe<l  as  K.  iidiltiii  on  i)age  160. — T.  W.  8. 
290 


U.    S.    GEOLOGICAL    SURVEY 


Monograph  xliv     Pl.  xiX 


ENGONOCERAS. 


PLATE  XX. 


291 


platp:  XX. 

Engonoceras. 

Page. 

Figs,  l-.'i.  Engonoceras  serpmtinum  (Cragin  ) 162 

Fig.  1.  Suture  showing  all  of  one  side,  part  of  the  other  and  dorsal  suture,  X  2. 

2,  3,  _  4.  Three  views  of  one  of  Cragin's  figured  types. 

•5.  Suture  of  same,  X  2. 
NearDenison;  Washita  epoch;  Coll.  Cragin,  Colorado  College. 

Figs.  6-13.  Enc/onoceras  pierdmiale  (von  Buch) 16-5 

Figs.  6,    7.  Specimen  from  Towash,  Tex.;  Coll.  Mus.  Comp.  ZooL,  Camliridge. 
8.  Suture  of  same,  X  2. 
9,  10.  Specimen  from  near  Cerrogordo,   Ark.;  Coll.   V.   S.    Nat.   Mus.,   No. 
22643. 

11.  Suture  of  same,  natural  size. 

12.  Specimen  from  Seven  Knobs,  ?,  miles  southeast  of  Glenrose,  Tex. 

13.  Suture  of  same,  X  2. 
Fredericksburg  group,  Comanche  series. 

292 


U.    S.    GEOLOGICAL  SURVEY 


MONOGRAPH   XLIV       PL.    XX 


a.a  fSft  ??=>  ^ 


13 


engonocEras, 


PLATE   XXI. 


293 


PLATP]    XXI. 

Engonoceras. 

Page. 

Fid.    1.  Enijonocerns pierdenale  \ar.  commt.nn' Hyatt 165 

Fig.    1.  Suture,  X  2.     Bell  County,  Tex.;  Fredericksburg  group,  Comanche  series. 
Coll.  U.  S.  Nat.  Mus.,  Xo.  8301. 

Figs.  2-6.  Engonoceras  subjeclum  Hyatt 168 

Figs.  2,  3.  A  specimen  from  Gabriel,  Williamson  County,  Tex. ;  Con.  Mus.  Comp. 
Zool.,  Cambridge. 

4.  Portion  of  septum  of  same  spei'imf  n — the  middle  one  of  the  three  indis- 

tinctly shown  in  fig.  2,  x  2. 

5.  Last  septum  of  same  specimen,  X  2. 

6.  Septum  of  a  smaller  specimen  from  same  locality,  X  2. 
Washita  (?)  group,  Comanche  series. 

294 


U.    S.   GEOLOGICAL   SURVE 


MONOGRAPH    XLIV       PL 


ENGONOCERAS. 


PLATE  XXII. 


295 


PLATE    XXII. 
Engonoceras. 

Page. 

Figs.  1-5.  Engonoceras  suijectum  Hyatt 168 

Fig.  1.  Specimen  from  Duck  Creek  beds,  near  Denison,  Tex. ;  Coll.  U.  S.  Geol.  Surv. 

2.  Suture  of  same,  very  slightly  abraded,  X  2. 

3.  Specimen  from  Grayson,  Tex.;  Coll.  D.  S.  Martin. 

4.  Suture  of  same,  X  2. 

5.  Suture  of  specimen   from  Tarrant  County,  Tex.;    Coll.   Cragin,  Colorado 

College. 
Washita  (?)  group,  Comanche  series. 

Figs.  6-10.  Engonoceras  gibboKum  Hyatt  171 

Fig.    6.  Lateral  view  of  a  small  specimen  from  Goodland  limestone,  15  miles  west 
of  Denison;  Coll.  V.  S.  Geol.  Surv. 

7.  Ventral  view  of  same,  partly  restored. 

8.  Septum  of  same,  X  2. 

9.  Fragment  doubtfully  referred  to  the  species,  from  Bell  County,  Tex. ;  Coll. 

V.  S.  Nat.  Mus.,  No.  8301a,  X  2. 
10.  Septum  of  same,  partly  rc.s^tored,  >;  2. 
Fredericksburg  group,  Comanclie  series. 

296 


U.   S.   GEOLOGICAL   SURVEY 


MONOGRAPH    XLI^       PL.    XXII 


ENGONOCERAS. 


PLATE  XXIII. 


297 


PLATE    XXIII. 
Engonoceras. 

Page. 

Figs.  1-6.  Engonoceras  gibboftum  Hyatt 171 

Figs.  1,  2.  Specimen  from  Cook  County,  Tex. ;  my  rollection. 
3.  Suture  of  same,  X  2. 

i,  5.   A  fragment  from  tiie  Goodland  limestone,  1.5  miles  .«JOUthwest  of  Gaines- 
ville, Tex. 
6.  Suture  of  same,  X  2. 
Fredericksburg  group,  Comanche  series. 

Figs.  7-9.  Engoiiocerds  Motteyi  Bohm 175 

Figs.  7,  8.  Young  specimen  in  Cragin  Collection,  Colorado  College. 
9.  Suture  of  same,  X  2. 
Fredericksburg  group  [?],  Comanche  series. 

298 

( 


U.    S.   GEOLOGICAL   SURVEY 


MONOGRAPH    XLIV      PL.   XXIII 


^ 


¥g 


r    Ifar-"'- 


% 


^J\ 


/ 


s^ 


#4 


ENGONOCERAS. 


PLATE  XXIV. 


299 


PLATE    XXIV. 
Engoxoceras. 

Page. 
Figs.  1-5.  Engonoceras  stoUeyi  Bijhm • 1~5 

Figs.  1,  2.  Specimen  in  my  collection,  partly  restored. 

3,  4.  Specimen  in  Coll.  Hill,  U.  S.  Geol.  Surv.  ["Hill  4a."]  (?) 
.5.  Suture  of  same,  X  2.     This  is  somewhat  worn  down. 
Fredericksburg  group  [?],  Comanche  series. 

Figs.  6-8.  Engonoceras  complicalnm  Hyatt 1'5 

Figs.  6,  7.  Type  specimen  from  near  Austin,  Tex.     Coll.  Hill,  U.  S.  Geol.  Surv. 
8.  Suture  of  same,  X  2. 
Comanche  Peak  limestone  of  Fredericksburg  group,  Comanche  series. 

300 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   XLlV       PI.   XXIV 


ENGONOCERAS. 


PLATE   XXV. 


301 


PLATE    XXV. 
Neolobites,  Metengonoceras. 

Page. 

Figs.  1-4.  Neolobites  chqfatl  Hyatt 1~8 

Figs.  1,  2.  Copies  of  Choffat's  figures  3a,  3b,  published  as  N.  vibrayeanus. 
3,  4.  Suture  of  probably  the  same  species  (after  Choffat). 
Cenomanian;  Portugal. 

Figs.  5-9.  Melengoiioreras  inscriptmn  Hyatt 180 

Fig.   5.  Section  of  fragmentary  specimen   from  west  of  Walnut  Springs,  Texas- 
Coll.  Cragin,  Colorado  College. 

6.  Suture  of  same,  enlarged. 

7.  Suture  of  a  small  fragmentary  specimen  from  12  miles  northwest  of  Decatur, 

Tex.;  Coll.  U.  S.  Geol.  Surv. 

8.  Suture  of  fragment  from  15  miles  west  of  Denison,  Tex.;  Coll.  U.  S.  Geol. 

Surv. 

9.  Ventral  view,  partly  restored,  of  specimen  from  12  miles  northeast  of 

Decatur,  Tex.     For  other  figures  see  PI.  XXVI. 
Fredericksburg  group,  Comanche  series. 

302 


U.    <=:    GEOLOGICAL    SURVEr 


MONOGRAPH  XLIV       PL.    XXV 


NEOLOBITES,    METENGONOCERAS. 


PLATE   XXVI. 


303 


PLATE    XXVI. 

Metengonoceras. 

Page. 

Figs.  1^.  Metengonoceras  inscriptum  Hyatt 180 

Fig.  1.  Enlarged  suture  of  specimen  represented  by  figs.  2  and  3,  and  by  PI.  XXV, 
fig.  9. 
2,  3.  Specimen  from  12  miles  northeast  of  Decatur,  Tex. 

4.  Suture  of  large  fragment  from  9  miles  from  Austin,  on  Beecaves  road. 
Coll.  IT.  S.  Geol.  Surv.     [This  drawing  was  labeled  M.  ambiginiiii,  but  the 
specimen  is  described  under  M.  inscriptum. — T.  W.  S.] 
Fredericks^burg  group,  Comanche  series. 

Figs.  5-7.  Metengonoceras  ambiguum  Hyatt 183 

Fig.  5.  Side  view  of  type. 

6,  7.  Suture  of  same  specimen,  X  2. 
Nine  miles  from  Austin,  on  Beecaves  road;  Fredericksburg  group,  Comanche 
Peak  limestone,  Comanche  series.     Coll.  U.  S.  Geol.  Surv. 

Fig.  8.  Metengonoceras  aculum  Hyatt 184 

Side  view  of  fragmentary  type  specimen. 

Elm  Fork,  Dallas  County,  Tex.;  probably  Eagle  Ford  shales,  Upper  Cretaceous. 
Coll.  Mus.  Comp.  2tool.,  Cambridge. 

304 


U.   S.   GEOLOGICAL    fiURvEV 


MONOGRAPH  XLIV       PL. 


6 


^     ^      f^      %     '     ^    ^''^*^' 

7 

A.  f-^' ^-^M '..>,•  MX^ 


r 


METENGONOCERAS. 


PLATE  XXVII. 


Mox  XLiv— 03 20  305 


PLATE    XXVII. 
Metengonocekas,  Flacenticeras. 

Page. 
Fiiis.  1-2.  Meteiir/imorerus  acutuni,  Hyatt .■ 184 

Fig.      1.  Ventral  view  of  type  specimen. 
2.  .Septum  of  same,  X  2. 
Elm  Fork,  Dallas  County,  Tex.,  probably  Eagle  Ford  shales,  Upper  Cretaceous. 
Coll.  Mus.  Comp.  Zool.,  Cambridge. 

Fuis.  3- 14.  Metengonoceras  dumhli  ( Cragin) 18.5 

Figs.    3, 4.  Lateral  and  ventral  views  of  specimen  described. 

5.  Section  of  same. 

6.  Inner  whorls  of  fig.  5,  enlarged. 

7.  Center  of  same,  still  more  enlarged,  showing  antisiphonal  lobe,  the  inner- 

most whorls  having  dropped  out. 

8.  Section  of  whorl  in  neanic  stage,  X  10. 
e.  Adult  lateral  suture,  X  2J. 

10.  Last  lateral  suture,  X  2J.  > 

11.  Dorsal  suture  continuous  with  lig.  9,  enlarged. 

12.  Dorsal  suture  one-fourth  volution  older  than  fig.  11,  enlarged. 

13.  Lateral  and  part  of  dorsal  suture  of  neanic  stage,  X  18. 

14.  Dorsal  suture  of  somewhat  later  substage  than  fig.  13,  enlarged. 

Four  miles  east  of  Whitesboro,  Tex.;  Eagle  Ford  shales.  Upper  Cretaceous;  Coll. 
U.  S.  Geol.  Surv. 

Ficis.  1.")-!  7.   Phiceidiceras  syrUde  (Morton ) J 205 

Fig.    15.  Suture  of  the  type  in  Coll.  Acad.  Nat.  Sci.  Phila. 

16.  Lateral  suture  of  var.  halei,  Coll.  Bost.  Soc.  Nat.  Hist.,  No.  8577. 

17.  Dorsal  suture  of  older  part  of  same  volution  as  fig.  16. 
Greene  County,  Ala.;  Eutaw  beds  (?),  Upper  Cretaceous. 

306 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   XLIV       PL.    XXVIJ 


"JiiA  ^Jn.-'it.  V?     ' 


'^■•*'*'*"^ 


17 


METtNGONOCERAb     PLACENT  IC  t  RAS 


PLATE  XXVIII. 


307 


PLATP]    XXVIII. 

Placenticeras  syrtale  (Morton). 
(Page  205.) 

Fics.  1,  2.  Two  views  of  tlie  type,  Coll.  Acad.  Nat.  Sci.  Phila.     (For  suture,  see  PI.  XXVII, 
%.  15.) 
3,  4.  Type  of  var.   Iiah-i,  Bost.  Soc.  Nat.  Hist.,  No.  8.577.     (For  suture,  see  PI.  XXVII, 

figs.  16  aud  17.) 
5,  6.  Another  specimen  of  var.  lialei,  same  collection. 

Eutaw  bed8(?).  Upper  Cretaceous,  Greene  County,  Ala. 

308 


U.    S.    GEOLOGICAL    SURVEY 


MONOGRAPH    XLIV       PL.    XX 


PLACENTICERAS. 


PLATE  XXIX. 


309 


PLATE   XXIX. 

Placenticeeas  GUADALUPE  (Roemer). 

(Page  197.) 
Fig.  1.  Lateral  view  of  a  large  specimen. 

2.  Aperture  view  of  same  considerably  restored. 
?>.  Section  of  same. 

4.  Enlarged  section  of  inner  whorls  of  same. 
Xear  Fort  Worth,  Tex.;  Taylor  beds  (?);  Upper  Cretaceous;  my  collection. 

310 


U.   S.   GEOLbcrCAL   SURVEY 


MONOGRAPH    XLIV       PL.    XXI>i 


PLACENTICERAS. 


PLATE  XXX. 


311 


PLATE   XXX. 

Placenticeras  sancarlosense  Hyatt. 
( Page  200. ) 

Fig.  1.  Side  view  of  an  average-sized  specimen 

2.  Aperture  view  of  same. 

3.  Suture  of  same,  X  2. 

San  Carlos,  Presidio  County,  Tex. ;  San  Carlos  beds  ;  Upper  Cretaceous ;  Coll.  V.  S.  Geol.  Snrv. 

312 


U.   S.   GEOLOGICAL  SURVEV 


Monograph  vliv     pl.  xxx 


PLACENTICERAS. 


PLATE  XXXI. 


313 


PLATE    XXXI. 

Placenticeras. 

Page. 

Figs.  1,  2.  Placenticeras  sancarlosense  Hyatt 200 

Fig.  1.  Section   of  a  small   specimen — "passage   form    between  this   specie.?  and 
guadalupse." 
2.  Side  view  of  same. 
San  Carlos,  Presidio  County,  Tex.;  San  Carlos  beds,  Upper  Cretaceous;  Coli.U.  S. 
Geol.  Surv. 

Figs.  3-5.  Placenticeras  nev)herryi  Hyatt 203 

Fig.  3.  Side  view  of  the  type  specimen. 
4.  Section  of  same. 
■5.  Aperture  view  of  same. 
Near  Presidio  Del  Norte,  Chihuahua,  Mexico;  San  Carlos  beds.  Upper  Cretaceous; 
Coll.  Columbia  University,  No.  10073G. 

314 


b.   S.   GEOLOGJCAL  SURVEY 


MONOGRAPH     XLIV       PL. 


PLACENTICERAS 


PLATE  XXXII. 


315 


PLATE     XXXII. 
Placenticeras  sancarlosense  var.  pseudostktale  Hyatt. 

(Page  200. ) 

Side  view  of  type  of  variety  (see  PI.  XXXIII,  tig.  1). 

Near  Fort  Worth,  Tex.;  Taylor  beds  (?),  Upper  Cretaceous;  my  collection. 

316 


U.   S.   GEOLOGICAl     SURVEY 


MONOGRAPH    >L1V       PL.    XXXII 


PLACENTICERAS 


PLATE  XXXIII. 


317 


PLATE   XXXIII. 
Placenticeras. 

Page. 
Fii;.  1.   Placenticeras  sancarlosense  var.  pseudo»yi-lale  Hyatt 200 

Fig.  1.  Aperture  view  of  specimen  figured  on  PI.  XXXII. 
Fias.  2-4.  Placenticenis  planum  Hyatt 202 

Fig.  2.  Aperture  view  of  medium-sized  specimen  partly  res^tored. 

3.  Side  view  of  same. 

4.  Peripheral  view  of  another  specimen  showing  less  development  of  nodes. 

(See  PI.  XXXIV,  fig.  1.) 
San  Carlos,  Presidio  CViunty,  Tex.;   San  Carlos  beds.  Upper  Cretaceous;  Coll. 
V.  S.  Geol.  Survey. 

318 


U.    S.    GEOLOGICAL    SURVE 


PLACENTICERAS- 


PLATE  XXXIV. 


PLATE    XXXIV. 

Placexticeras  plaxcm  Hvatt. 

(Page  202.) 

Fig.  1.  Side  view  of  the  small  specimen  rejiresented  by  PI.  XXXIII,  fig.  4. 
2,  .3.  Aperture  and  side  views  of  a  larger  specimen. 
San  Carlos,  Presidio  County,  Tex.;  San  Carlos  beds,  Upper  Cretaceous;  Coll.  U.  8.  Geol.  Survey. 

320 


U.   S.   GEOLOGICAL   SURVEY 


MONOGRAPH    XLIV       PL.    XXXIV 


PLACENTICERAS. 


PLATE   XXXV. 


MON  XLIV— 03 21  321 


PLATE    XXXV. 

Placenticeras  intercalare  Meek. 

(Page  207.) 

Figs.  1,  L'.     Side  and  aperture  views  of  medium  specimen  (see  PI.  XXXVI,  fig.  1). 
[Black  HilLs?],  Fort  Pierre,  Upjier  Cretaceous;  Coll.  Yale  University  No.  1863. 

322 


U.    S.   6E0LOGICAL  SURVEY 


MONOCRAPH     XLIV       PL.    XXX^ 


PLACENTlCERAb 


PLATE   XXXVI. 


323 


PLATE    XXXVI. 

Placenticeras  iNTERCALARE  Meek. 
(Page  207.) 

Fifi.  1.  Opposite  side  of  specimen  figured  on  PI.  XXXV. 

2,  3.  Side  and  aperture  views  of  small  specimen,  No.  21041). 

4.  Suture  of  same,  X  2. 

5.  Parts  of    two  septa  of   Geological    Survey   specimen   from   Harper,  Wyo.,  represented   by 

PI.  XXXVII,  figs.  1,  2. 
Fort  Pierre,  Upper  Cretaceous,  Coll.  Yale  University  (except  fig.  5). 

324 


U.   5.   GEOLOGICAL   SURVEY 


MONOGRAPH    XLIV      PL.   XXXVl 


PLACENTICERAS. 


PLATE  XXXVII. 


325 


PLATE    XX  XY  II. 

Placekticeras  inteecalare  Meek. 

{Page  207.) 

Figs.  1,  2.  Fragmentary  small  specimen  from  near  Harper,  Laramie  Plains,  Wvo. ;  Coll.  U.  S.  Geol. 
Survey.     (See  PI.  XXXVI,  fig.  5. ) 

3.  Section  of  specimen  "approximating  to  some  varieties  of  P.  sliuilinil,"  from  Ponil  t'anyon, 

New  Mex.;  Coll.  U.  S.  Nat.  Mus.,  No.  9735. 

4.  Side  view  of  same  specimen.     (For  suture,  see  PI.  XXX VIII,  lig.  1.) 

^lontana  group,  Upper  Cretaceous. 

326 


U.   6.   GEOLOGICAL   SURVEV 


Monograph  xliv     pl.  xxxvil 


PLACENTICERAS. 


PLATE  XXXVIII. 


327 


PLATE    XXXVIII. 
Placenticeras. 

Page. 

Fig.  1.  Placenticeras  intercalare  Meek 207 

Suture  of  specimen  from  near  Harper,  Wyo.     (See  PI.  XXXVII. ) 
Montana  group,  Upper  Cretaceous. 

Fig.  2.   Placenticeras  intercalare  var.  costalitm  Hyatt 207 

Side  view  of  type  of  variety,  my  collection,  purchased  from  Ward.    "Probably  from 
Black  HilKs  S.  Dak. 
Montiina  group,  Uppjr  Cretaceous. 

328 


U     S.    GEOLOGICAL   SURVEY 


MONOGRAPH   XLIV 


PLACENTICERAS. 


PLATE   XXXIX. 


329 


PLATE    XXXIX. 
Placenticekas. 

Fi(is.  1,  2.  Phwenlicenix  hitercalare  var.  costatum  Hyatt L'n7 

Figs.  1,  2.  Aperture  view  and  suture  of  specimen  repreeenteil   1>v  PL  XXX^'I1I, 
fig.  2. 

Fk;s.'  3-6.  Fliicevlicetris  placenta  ( Dekay ) 211 

Fig.    3.  Fragment  of   a  small   specimen  from  Chesapeake  and   Delaware  Canal, 
Coll.  Acad.  Nat.  Sci.  Phila. 

4.  f~uture  of  same,  X  2. 

5.  Side  view  of  small  specimen  from  Leni>la,  N.  J. 

().  Sutures  from  smaller  end  of  volution   rejn'e-^ented   l)y  lig.  5  enlarged  four 
diameters  (see  PI.  XL,  figs.  1,  2). 
Matawan  CM  formation,  Upper  Cretaceous.. 

330 


U.   S.    GEOLOGICAL    SURVEV 


MONOGRAPH    XLIV      PL.   XXXIX 


V 


PLACENTICERAS. 


PLATE   XL. 


331 


PLATE   XL. 
Placentickras. 

Page. 

Figs.  1,2.   Placentireras  phicenta  ( Dekay  1 - 211 

Fig.    1.  Peripheral  view  of  .specimen  represented  by  PI.  XXXIX,  fig.  h. 
2.  Side  view  ot  same,  enlarged  nearly  two  diameter.'*. 

Figs.  8-7.  Placenticerax  slantoni  var.  bolU  Hyatt 214 

Figs.  3,  4.  Aperture  and  side  views  of  the  small  specimen   from  Tarrant  County, 
Tex.,  in  tlie  Martin  collection,  Rutgers  Female  Institute,  described  liy 
Meek  as  P.  intercalare. 
ri.  Suture  of  same,  X  2. 

6.  Fragmentary  specimen  from  Horton's  mill,  Dallas  t'onnty,  Tex.;  Coll.  Mas. 

Comp.  Zool.,  Cambridge. 

7.  Lateral  and  internal  suture  of  same,  X  2.     (See  PI.  XLI.) 
Taylor  beds  (?),  Upper  Cretaceous. 

332 


U.    S.   GEOLOGICAL    SURVEY 


MONOGRAPH    XLIV       PL.    XL 


PLACENTICERAS. 


PLATE  XLI. 


333 


PLATE    X  L  I . 

Placenticeras  stantoxi  \ur.  v.otaa  Hyatt. 

(Page  214.) 

Fui.  ].  Sectional  view  of  gpeciraeii  represented  l)y  PL  XL,  ligs.  6  ami  7. 
2.  Restored  section  of  same. 
3,  4.  Living  chamber  of  a  larger  speeiirieii. 

5.  Last  suture  of  same  specimen. 
6, 7.  Living  chamber  of  another  specimen. 
Horton's  mill,  Pallas  County,  Tex.;  Taylor  beds  (?),  Upper  Cretaceous;  Coll.  Mns.  Comp.  Zool., 
Cambridge. 

3.34 


S.    GEOLOGICAL    SURVE 


MONOGRAPH    XLtV       PL.    XLI 


PLACENTICERAS. 


PLATE    XLII. 


335 


PLATE    XLII. 
Placenticekas  stantoni  viir.  holli  Hyatt. 

(Pafre214.) 

Fig.  1.  Suture  iif  young  specinieii  enlarged  abmit  'J\  diameters. 
2.   Part  of  living  chamber  ami  last  septa  of  a  large  specimen. 

Hurton'.s  mill,  Dallas  County,  Tex.;  Taylor  beds  (?),  Upper  Cretaceous;  Coll.  Mus.  Comp.  Zool. 
Cambridge. 

336 


U.   S.   GEOLOGICAL   SURVEY 


MONOGRAPH    XLIV       PL.    XLII 


PLACENTICERAS. 


PLATE    XLIII. 


MON  XL1\— 03 23  '  337 


PLATE    XLIII. 
Placenticekas. 

Page. 

Figs.  1,  2.  Placentireras  stantorii  var.  hoUi  Hyatt 214 

Fig.  1.  Side  view  of  small  costate  specimen. 
2.  Suture  of  same,  X  2. 
Horton's  mill,  Dallas  County,  Tex.;    Taylor  beds   {?),  Upper  Cretaceous;   Coll. 
Mus.  Com  p.  Zool.,  Cambridge. 

Figs.  3-11.  Placeniiceras  jjseudojdaccntd  Hyatt 216 

Fig.  3.  Side  view  of  small  fragmentary  specimen. 
-1.  Sectional  view  of  same. 

5.  Center  of  .same  enlarged. 

6.  Ventral  view  of  first  whorls  of  same  specimen  much  enlarged. 

7.  8.  Inner  whorls  of  another  specimen,  natural  size. 

9,  10.  Lateral  sutures  of  last  whorl  of  .same  as  indicated  on  tig.  7. 
Upper  Kanab  Valley,  Utah;  Colorado  group;  Upper  Cretaceous ;  Coll.  U.  S.  Xat. 
Mus.,  No.  22.344. 

11.   Parts  of  internal  sutures  of  ephebic  stage  when  dorsoventral  diameter  of 
volution,  measures  49  mm. 
Muddy  Creek,    Huerfano  County,   Colo.;   Fort  Benton  formation:    Upper   Cre- 
taceous; Coll.  U.  S.  Nat.  Mus.,  No.  22199. 

338 


U.   S.   GEOLOGICAL   SURVE' 


MONOGRAPH   XLIV      PL.    XLIII 


PLACENTICERAS. 


PLATE   XLIV. 


3S9 


PLATE     XLIY. 

PlACENTICERAS   PSEUDOrLACENTA    Hyatt. 

(Page  216. ) 

Figs.  1,  2,  3.     Three  viewy  of  living  chamljer  of  fragmentary  .specimen. 
Bad  Lands,  near  Black  Hills;  Upper  Cretaceous,  S.  Dak.;  luy  collection. 

340 


U.   S.   GEOLOGICAL    SURVEY 


MONOGRAPH    XLIV      PL.   XLIV 


PLACENTICERAS. 


PLATE    XLV. 


841 


PLATE    XLV. 
Placenticeras. 

Page. 

Figs.  1,  2.  Plcicmticeras  pseudoplacenta  var.  occidentale  Hyatt . .       217 

Fit;.      1.  A  .specimen  from  the  Tapper  Missouri  River;  Coll.  Coliiml.iia  I'niversity, 
No.  10C22G. 
2.  Suture  of  a  young  specimen  from  Hortou's  mill,   Dalhis  County,  Tex.; 
Coll.  Mus.  Comp.  Zool.,  Cambridge. 

Ficis.  3-16.   Placenticeras  whitfieldi  Hyatt 221 

Fig      3.  Side  view  of  small  fragmentary  specimen  from  Clifford,  Nebr..  in  Coll. 
Mus.  Comp.  Zool.,  Cambridge,  enlarged. 

4.  Section  of  same  showing  venter  of  earliest  whorls,  X  3. 

5.  Center  of  same,  X  about  6i  diameters. 

6.  F''irst  two  sutures  and  beginning  of  siphuncle  of  same  specimen,  nmch 

enlarged. 

7.  Beginning  of   sijihuncle  of  same   after  etching  with   acid,    siill    further 

enlarged, 
8-10.  Early  stages  obtained  by  breaking  down  a  larger  specimen  from  the 
Black  Hills,  South  Dakota,  in  my  collection;  enlarged  about  5  diameters. 
1 1-14.  Complete  sutures  from  dorsum  to  venterof  same  stages  as  figs.  8,  9,  10. 
Fig.  11  is  earliest  suture  visible  on  tig  9;  lig.  12  is  on  last  quarter  of 
same  whorl;  fig.  13  is  last  .suture  on  iig.  10,  and  fig.  14  is  nearly  a  volution 
earlier. 

15.  Dorsal  (internal)  sutures  at  diameter  cif  15  nun. 

16.  Same  at  diameter  of  40  nun.     The  last  two  figures  may  not  be  from  same 
specimen  as  figs.  8-14. 

Montana  grou[(,  Upper  Cretaceous. 

342 


S.    GEOLOGICAL    SURVEY 


MONOGRAPH    XLIV       PL.    XLV 


'   r-.  <'-^   <-i  y^ 


PLACENTICERAS. 


PLATE   XL VI. 


343 


PLATE   XLVI. 

Placenticeras  whitfieldi  Hyatt. 

(Page  221.) 

Figs.  1,  2.  Two  views  of  a  large  specimen,  tV  actual  diameter. 

Black  Hills,  South  Dakota;  Montana  formation,  Upper  Cretaceous;    Coll.   Bost.   Soc.   Nat  Hist., 
No.  11124. 
344 


PLATE   XL  VII. 


345 


PLATE    XLYII. 
Placenticeras. 

Page. 
Figs.  1-4.     Placenticeras  whitfieldi  Hyatt 221 

Figs.  1,  2.  Two  views  of   the  inner  whorls  of  a  small  specimen  from  the  t'pjier 
Missouri;  Coll.  V.  S.  IS^at.  Mus.,  No.  18936. 
">.  Fragment  showing  peculiar  sculpture  of  the  inner  shell  layers.  j)riilialily 

from  Black  Hills,  South  Dakota;  my  collection. 
4.   Another  specimen  showing  similar  sculpture  from  same  collection  and 
region. 
Montana  group,  Ujiper  Cretaceous. 

Fig.       5.     Placenticeras  whitfieldi  var.  tuberculatum  Hyatt 232 

Fig.        5.  Side  view  of  the  type  of  the  variety. 

Montana  group,  Upper  Cretaceous;  Black  Hills,  South  Paknta;  my  collecticm. 

Figs.  6-8.     Placenticeras  sjAUmani  Hyatt 233 

Figs.  6,  7.  Two  views  of  the  fragment  on  which  the  species  is  based. 
8.  Part  of  weathered  suture  of  same. 
Ripley  formation  f?),  Upper  Cretaceous;  Mississippi  (?);  Coll.   Acad.   Nat.  Sci. 
Phila. 
[Note. — Professor  Hyatt  indicated  that  the  drawings  for  tigs.  6  and  7  were  unsatisfactory 
to  him,  but  the  specimen  is  too  imperfect  to  serve  as  the  basis  for  a  restoration]. 
346 


S.    GEOLOGICAL    SURVEY 


MONOGRAPH    >LIV       PL.    XLVII 


PLACENTICERAS 


INDEX, 


[Names  in  italic  are  synonyms;  fi^i^ires  in  bljick-fiu'c  type  are  numbers  of  pages  on  which  deseriptions  appear:  figures 
in  italic  denote  illustrations.] 


Page. 

Acanthoceras 27 

spiniferum  Whiteaves 110 

Acceleration  of  development 19-23.189-190 

Acompsoceras  Hyatt 105,  note;  111-112 

bochumense  (Schliiter) H 1-1 12 

essendense  fSchliiter) 112 

renevieri  (Sharpe) 112 

Aconeceras  Hyatt J^8. 100. 101,  note 

nisum  (d'Orbigny) 90,99.100,270 

Agassiceras 24 

striarles 24 

Amaltheus  chrayi  de  Loriol 234 

Ammonites 43 

aUni  naius  Gabb ; 152 

haiduri  Keyserling 191. 192, 244 

belvidcrends  Cragin 158 

bidorsatus  Roemer 243, 244 

bilobiitus  Gabb 30 

caicffli  Karsten 133 

catilf'i.'i  d'Orbigny 143 

clypci/onais  d'Oihigny 85 

Cf>mprcssissimus  d'Orbigny 142 

concHiaiiis  Stoliczka 107 

cou/o;u' d'Orbigny 114 

crnmtesta  Stoliczka 107 

eunliffi.  Stoliczka 107 

dccidnus  Hyatt 107 

r^V/o //a" 'AS  d'Orbigny 131,136,138 

dispnr  d'Orbigny 141 

domei/kanus  Bayle  and  Coquand 115 

dumasianns  d'Orbigny 139 

euomphalus  Sh&Tpe 107 

civaldi  von  Buch 4G,  48 

gahcitus  d'Orbigny 135. 136, 142 

gcirilinnus  d'Orbigny 84.90 

guadalupce  Roemer 197, 241 

haplnphijlla  Redtenbacher 48 

harttit  ( Hyatt) 103 

hdcr»jdeurus  (Neumayr  and  Uhlig) 90 

lafidavius  Sharpe Ill 

Icvtirt/lnris  Owen 71-75 

lindUji  Karsten 134 

lobata  Tuomey 66 

mammUlaris 108-110 

viammillatus 108 

mantdli  Sowerby 114, 115, 141 

marcousnrnis  d'Orbigny 90 

milfrri  Hauer 239 

mo8(7ix/«  d'Orbigny 84 

7it8HB  d'Orbigny 100 

nodosoides  Scbliiter llj 

orbif/nyanus  Geinitz 235, 240 

pcdrrnafis  Roemer 59, 64, 82, 153, 165 


Page. 
Ammonites— Continued. 

pierdenalis  von  Bnch 157, 165 

placenta  Dekay 211 

pleuriscpta  Conrad 59 

polyopsis  Dujardin 206, 207, 237, 240, 243 

provincialis  d'Orbigny 131 

jiulchellus  d'Orbigny 138. 140, 141 

renevieri  Sharpe 112 

rcquieniamis  d'Orbigny 99, 100 

robini  ThiolUere 46 

rotomagcnsis  Defrance 107 

roj/cri'am(8 d'Orbigny lUl.note 

Tiisticiis ]  06,  note 

siva  Forbes 83 

sivaMoi>i  Shumard lis 

sijriarus  von  Buch 32, 146-150 

s-i/rtali n  UoTtou 205,207,237 

syrtalis  var.  orbig-dyanus  Schluter 235, 241, 242 

si/Halls  var.  polyopsis  Schluter 239 

iamulitms  Blanford 241 

tcli/er  Morton 233 

truelU 19 

uskas  Stoliczka 115 

vibraycanus  d'Orbigny 149, 178, 240 

i>ici7ialis  Stoliczka 115 

x^ielbanci  d'Orbigny no 

woolgari  Mantell 110 

Ammonitinse 19:5,195-197,224 

Cretaceous 102 

disappearance  of  characters 23 

of  the  Jura,  relation  to  those  of  the  Cretaceous 19-20 

Arietidse 19 

Arrestation  of  development 20-23 

Aspidoceras 19, 106, 116 

Baculites 21 

Barroisiceras  Grossouvre 26,  '27, 104, 112 

desmoulinsi  Grossouvre 105 

liaberfellneri  Grossouvre 104 

liaueri  Grossouvre 105 

Bathmoeeras 68,  note 

Buchiceras  Hyatt 25,26,27,84,88,112,144,145,191-193 

atteriuatam  Hyatt 33, 151 

belviderense  Cragin 158 

bilobatum 25, 27-29, 30, 31 ,  191, 25/, 

ewaldi  (von  Buch) 40.44,46,51 

/o?/rHr^i  Bayle 45,51 

hartUi  ( Hyatt) 103 

serratum  Hyatt 51-54 

slizewiczi  Fallot 49 

swallovi  (Shumard) 122 

tissoti  Bayle 42 

Buchiceratidse  Hyatt 24, 26, 35, 144 

Calycoceras  navicularis 113 

347 


348 


INDEX. 


Page. 

Cardioceras 245 

Carstenia  Hyatt 129, 130, 133-IS4 

caicedi  ( Karsten) 133-135 

gftleata  (tVOrbigny) 135 

liiuiigi  (Karsten) 133,134 

subcaicedi  { Karsten) 134 

tuberculata  Hyatt 117, 134, 135, 136 

Ceratii€»  hartiii  Hyatt 103 

Ceratitinse 21 

Cheloniceras 101, note;  117,129 

royerianum 101, note;  116 

Choffaticeras  Hyatt 35, 37,  38 

barjonni  (Choffat) 37 

douyillei  (Peron) 38 

meslei  (Peron) 35,37,38 

Classification,  tabular  statement  of 15-18 

Coilopoceras  Hyatt 83,85,87-89,91,  100, 101, note 

colleti  Hyatt (11-94,  95,  272, 271, 

gros,souvrei  Hyatt 100,  S76 

noyimexieanum  Hyatt 91-93, 94-96,  97, 272 

requienianum  (d'Orbigny) 99 

springer!  Hyatt 96-99,  :.V6 

Coilopoceratida- 24, 88-100;  101,  note 

Cope,  Edward  D.,  on  acceleration  and  retardation  in 

development 20-23,189-190 

Coronites 101,130,note 

coronatoides 130,  note 

Cosmoceratida 101-105 

Cretacic,  nse  of  term 11 

Desmoceras 101,  note 

Desmoceratidfe 25 

Development,  acceleration  and  arrestation  of.  19-23, 189-190 

Diadochoceras  Hyatt 105. 100, 107 

nodosocostatum 106, 107 

Diplaemoceras  Hyatt 189, 192, 242-243 

bidorsatum  i  Roemer) 243 

canaliculatum  Hyatt 243-244 

Douvilleiceras  Grossouvre 10.5-107, 108-109, 113 

mammillare  (d'Orbigny) 109, 113 

orbignyi  Hyatt 110 

spiniferum  (Whiteaves) 110 

Eohinoids,  parallelism  in  local  development  of 195 

Engonoceras  Neumayr 20, 21, 58, 

14.5,  147,  153,156,  157-158,178-180,182,  196,198,242 

belviderense  (Cragin) 158-159, SS8 

complicatnm  Hyatt 175-177,300 

emarginatum  (Cragin) 1.59, 160, 177 

(labbi  Etihrn 153 

gibbosum  Hyatt 171-175,  «9S,  29S 

inscriptum 1,83 

pedcniafis  Bohm 165 

pierdenale  (von  Buch) 157,158, 165, 167, 170, 17.5,  J9J 

var.  commune  Hyatt 165-168, 291, 

retardum  Hyatt 160.  note;  290 

roemeri  (Cragin) 172, 177 

serpcntinum  (Cragin ) 162-164, 167, 171,  S,90,  S9S 

stolleyi  Bohm 157, 175, 29S,  SOO 

subjcctum  Hyatt 58. 161, 164, 168-171, 291,,  -296 

uddeni  (Cragin) 1.54, 158, 159-161, 175, 290 

Engonoceratidse 144, 145, 153-187, 193, 243 

Erymnoeeras 102 

Eulophoceras  Hyatt 83-85, 100 

natalcnse  Hyatt 86-87, 271, 

Eulophoceratidic 24, 83-S7 

Families,  clas.sifled  list  of 15-18 

Gabbioceras  batcsi  (Gahb ) 102 

Genera,  classified  list  of 1.5-18 


PagB. 

Gerhardtia  Hyatt 129, 130, 134, 135-136 

galcatoides  ( Karsten) 13.5 

galeatus  (Karsten) 136 

veleziensis  Hyatt 136 

GloUoceras  attenuatiLm  Hyatt 151,1.52 

Goniatitinte 21,74,102 

Heinzia  Sayn 101, 110, 117, 122, 128-130, 133, 135-137 

corioli  Xickles 1 30 

heinzi  Coquand 1 30 

hispnnica  Hyatt 131 

matura  Hyatt 116, 122, 128, 132-133, 2S2 

ouachen.sis  (Coquand ) 133 

ouachcnus  .Sayn 142 

provincialis  (d'Orbigny)...  117, 131-132, 133-136, 2«S,2M 

pulchelliformis  Hyatt 131.132 

sayni  Hyatt 130 

Heinziidfe 117.12S-136 

Hemi  tissotia  Peron 35, 36, 38 

batnensis  Peron 39 

caziui  Peron 39 

ceadouroensis  Choffat 40 

djelfensis  ( Peron) 40, 54 

morreni  (Coquand) 39, 40 

prsecipua 41 

tissotiseformis  Peron 40 

Heterotissotia  Peron 55 

neocera  tites  Peron 55-56 

Hoplites 101;  130,note:  193 

hoplitiformis 131,  note 

splendens 192, 193 

Hoplitid* 105;  131, note:  137,192 

Horizons,  table  of 18 

Hyperlioceras  discoidum 19 

subdiscoidum 19 

Hystatoceratidse 24, 26, 27 

Indoceras  Noetling 56 

acutodorsatum  ( Noetling) 57 

baluchistanense  Noetling 56-57 

Knemiceras  Bcihm 26, 30, 145, 192 

attenuatum  (Hyatt) 33, 151, 152, 2S6 

compressum  Hyatt 149-150, 152, 2SU 

var.  subcompressum  Hyatt 149, 150-151, 25i 

gabbi Hyatt lb2,2SS 

syriacum  (von  Buch) 146-149, 150, 2« 

uhligi  (Choflat) 152 

Knemiceratida; 144-152 

Lenticeras  Gerhardt 84-85.103 

andii 84-85 

Lenticeratidse 24 

Leptocampyli 25 

Libyeoceras  Hyatt 56, 57 

ismaele  (Zittel) 58 

Lophobolites  Hyatt 41, 137, 144 

cotteaui  (Nickljs) 144 

Mammitida 24,27;  101,  note;  109 

Mammitidie 24 

Mantelliceras  Hyatt 110,  111,  113 

oouloni  (d'Orbigny) 114 

domeykanum  (Bayle  and  Coquand) 115 

indianense  Hyatt 115 

mantelli  (Sowerby) 111,113,114 

picteti  Hyatt 114 

ushas  ( Stoliczka) 115 

vicinale  (Stoliczka) 115 

Mantelliccratida 105 

Mantelliccratida: 105-116,141 

Metacanthoplites  rhotomagensis  (Defrauce) 107 


INDEX. 


349 


Page. 

Metasigaloceras  Hyatt 106 

rusticum  (Sowerby) 106 

Metatissotia  Hyatt 43, 4o.  50, 55 

auressensis  (Peron) 49 

ewaldi  (von  Buch) 48,52 

fourneli  iBayle) 45,48 

haplophylla  { Redtenbacher) 48 

nodosa  Hyatt 4fi,  47,  48 

robini  (Thiolli^rei 45, 46-47, 4S 

slizewiczi  (Fallot) 49 

Metengonoceras  Hyatt 153-155, 158, 170, 179-180 

acutum  Hyatt 184-185, 187, 304, SOS 

ambiguutn  Hyatt 18S-1S4,  SOi 

dumbli  (Cragin) 180,185-187.306' 

inscriptum  Hyatt 180-183. 184, 185,  SOi,  SOi 

Metoicocera.s  Hyatt 101, 110, 113. 116-117, 129, 134 

acceleratum  Hyatt 127-128,  iSO 

gibbosum  Hyatt 121-12-2, 3S-' 

kanabense  Hyatt SSS 

swallovi  (Shumard) 117, 

1 18-131, 122, 123, 134, 274, 27S,  3S2 

whitei  Hyatt 118, 121, 122-127, 128,  i7S,  iSO 

Metoicoceratidae 115-128 

Mojsisoviesia  Steinmann 24-25, 26, 27, 89, 90 

dnrfeldi  Steinmann 25-26,  j?5i 

Mojsisovicsiidse  Hyatt 24 

Neolobites  Fischer 68, 104, 144, 158, 178 

choflati  Hyatt 178,302 

cnttfani  Xicklt^s 144 

peroni  Hyatt 179 

vibrayeanus  (d'Orbigny) 178, 179 

Neumayria 20 

aspidoides 19 

discus 19 

hochstetteri 19 

serrodens 19 

Nicklesia  Hyatt 136,137,138,140 

alicantensis  Hyatt 138 

bertrandl  ( Sickli'S) 138 

didayana  (d'Orbigny) 131,138 

dumasiana  (d'Orbigny) 138, 139, 2S6 

karsieni  ( I'hlig) 138 

lapparenti  (Nickl^s) 138 

lenHculata  (Hyatt) 188 

levyi  ( SicklOs) 138 

malladEc  (XicklOs) 138 

moltoi  (Nickles) 138 

nolani  (Nickles) 138 

pulcbella  (d'Orbigny) 141 

zeilleri  (Nickles) 138 

Odontoceras 105 

Olcostephanus 102 

Orthoceratites \ 68 

Oxynoticeras 104 

heteroplcurum  Neumayr  and  Uhlig 89-90 

pseudogranianum  Chlig 90 

Pachyeampyli 25 

Pachydiseus 90, 102 

Paralenticeras  Hyatt 84,  note;  85 

sieversi  Gerbardt 85 

Paratlssotia  Hyatt 41,45,50,65,143 

djelfensis 50 

ficheuri  (Grossouvre) 40,50,51,52 

fourneli  Grossouvre 52 

grossouvrei  (Peron) 49,50,54 

regularis  Hyatt .50. 53-54,  iSS 

.serrata  (Hyatt) 51-53.. 54, s,5« 

tbomasi  ( Peron) ,50 


Page. 

Pedioceras  Gerhardt 105, 1 08 

caquesensis 107 

cundinamarcEe  Gerhardt 107 

ubaquensis 107 

Pedioceratidge 105 

Peroniceratidse 24, 27 

Phricodoeeras 105 

Phyllocampyli 25 

Phylloceras 76, 88, 234 

Phylloceratidaj 100;  101,  note 

Placenticeras  Meek 20, 

22, 94, 140, 145, 153, 155, 178, 185, 188-196,  243, 244 

californicum 192,  note 

crassatum  Hyatt 241 

depressum  Hyatt 190,  237 

ebrayi  (de  Loriol ) 234-235 

fallax  Castillo  and  Aguilera 234 

J'litschi  Grossouvre 240 

grossouvrei  Hyatt 190, 191, 237-238 

guadalupae  ( Roemer) 188-191. 196- 

197-199. 200, 202-204:  206,  note;  211, 213, 237,  SIO 

iucisum  Hyatt 238 

intercalare  Sleek 190, 

196,  '205, 206,  207-21 1 ,  214-216, 221,  .^22-330 

lentieutare  Meek 71-75, 242 

Warriensf  Whiteaves 127,128 

memoria-scbloenbachi  Laube  and  Bruder 236 

milleri  (Hauer) 190,191,238,239 

ne-vvberryi  Hyatt 190, 191,196, '200, 203-205, '206,314 

orbiguyanum  (Geinitz) 240 

pacificum 192,  note 

placenta  (Dekay) 190;  191, note;  196, 20'2, 209, 

210, 211-214, 215-219, 221-223, 225, 233, 236,  SSO,  333 

placenta  var.  intercalare  Meek 207 

planum  Hyatt 190, 191, 196, 202-203, 204, 211, 518,  SSO 

polyopsis  (Dujardin) 240-241 

pseudoplacenta  Hyatt  189, 190, 

196, '214,  216-217. -232, 333, ,340 

var,  occidentale  Hyatt 217-220,342 

pseudorbignyanum  Hyatt 240.  242 

requieniauum  d'Orbigny 236 

sancarlosense  Hyatt  ....  191. 190, 200, 202,  '206, 211, 312.  Sli 

var.  pseudosyrtale  Hyatt 190, 

191, 197, 199,  200-202.  SIO,  SIS 

schliitcri  Hyatt 230,  239,  '241, 242 

spillmani  Hyatt 233, 346 

stantoni  Hyatt 189, 190, 196,  214, 217, 218,  '233, 236 

var.  boUi  Hyatt 207, 

212, 21 4-2 16, 219, 225, 226,  SS3-3S8 

sublilistriatum  Jimbo 242 

syrtale  (Morton) '22,189-191, 

196,  198,  200,  201,  203,  '204,  205-206,  20.8-213, 
215, 217, 220, 221,  232,  233,  236-239,  242,  SOr,.  308 

var.  halei  Hyatt 205, 206-207 

syrtale  var.  qtiadralum  Grossouvre '237 

tamulicum  (Blanford) '236.241-242 

telifer  (Morton) 233-234 

nhliyi  Choffat 1.52, 199, 235 

warthi  Kossmat 235-236 

wbitfieldi  Hyatt  22,189,190; 

191 .  note:  196, 208, 209, 211-220,  221-232, 236, 342-346' 

var.  tuberculatum  Hyatt 209, 214, '220, 2'21, 232 

Placenticeratidte 188-245 

Platylenticeras  Hyatt 84,  note;  85, 88-89.  '245 

gevriliauum  (d'Orljigny) 84,90 

heteropleurum  (Neumayr  and  Uhlig) 89-90,99.244 

pseudograsianum  (Uhlig ) 89, 90 


350 


INDEX. 


Page. 

Plesiotissotia 34, 41 

michaleti  Peron 41 

Polvplcctus  oapellinus 19 

iliscoides 19 

Primordialida- 224 

Prioniitropiflic 24, 27 

Prolecanites 74 

Protengonoceras  Hyatt 20, 

153, 157, 158, 179, 181, 186, 188, 189, 192, 198, 204 

emarginatum  (Cragin)  154,157,176 

gabW  (Bohin) 15:5-156, 176. ««6 

planum  Hyatt 156-157, f«S 

Pseudaspidoceras  Hyatt 106-107, 116 

coiieiliatum  (Stoliczka) 107 

crassitesta  (Stoliczka) 107 

cunliffi  (Stoliczka) 107 

dcciduum  Hyatt 107 

eiiomphalum  (Sharpe) 107 

footcanum  (Stoliczka) 106, 109 

schliiteri  Hyatt 107 

Pseudoceratites,  definition  of 13 

Pseudophyllites  Kossmat 25 

Pseudotissotia  Peron  34, 35^36, 37, 38 

Imrjonai  Clioffat 37 

douviUci  Peron 38 

galliennei  (d'Orbigny) 35,86,37.42 

meslei  Peron 37 

tunisiensis  Hyatt 36-37 

Pseudotissotiidfe  Hyatt 24,34-35 

Psiloceras 24, 25 

PsiloceratidsE' 25 

Psilopulchellia 136,137,142,143 

Psilotissotia  Hyatt 41, 137, 140, 141, 143 

clialmasi  (NicklSs) 143 

defforgesi  (Sickles) 143 

haugi  (NicklSs) 143,144 

mariolse  (NickWs) 143 

reigi  (Nickl^s) 143 

Pulrhellia  Uhlig 41. 

55, 112, 117, 129, 131, 136, 137, 139, 140-142,  144 

eaicedi  ( Karsten ) 130, 135 

changarnieri  Sayn 142 

Columbiana 142 

compres«issiina  (d'Orbigny) 141. 142. 2« 

curioli  Nickles 130 

defTorgesi  Nickles  143 

didayi  Gerhardt 136 

/ouqiiri  Nickles 139 

hnugi 143 

hdnzi  Sayn 130 

bet  tncri 142 

K-nrftini  Uhlig 138 

kiliani 133,142 

nicklesi  Hyatt 142 

ocMerti  NieklOs 139 

outtchen.'ds  Sayn 133, 142 

provinciaUs  d'Orbigny 129, 130, 131, 134 

pidehdla  d'Orbigny  . . : 138, 140, 141 

^auvarifaui  Hermite 139, 140 

schlumbergeri  NicklOs 142 

selecta  Gerhardt 142 

Kidicaicali  Sayn 1-29, 130 

I'ulchelliida; 30,101;  104,  note;  117,129,136-145 

Ketardation  in  development 20-23, 189-190 

Uoemeroceras  Hyatt 26, 80, 36, 112, 145, 192 

attenuatnm  (Hyatt) S3,«M 

denticulatum 34 


Page. 
Eoemeroceras  Hyatt— Continued. 

gabbi  Hyatt 30,31,256 

subplanum  Hyatt 84, 25S 

syriaciforme  Hyatt 30, 31-32, 33, 34, 37, gSU 

Scaphites 189 

Schlocnbachia 191, 193 

Schluetericeras  Hyatt 110-111 

laubei  Hyatt Ill 

michelobense Ill 

nodosoides  (Schliiter) 110,111 

vielbanci  (d'Orbigny) 110 

Sharpeiceras  Hyatt Ill 

inconstans  (Sehluter) 111,112 

laticlavium  ( Sharpe j Ill,  li;> 

schlueteri  Hyatt Ill 

Sigaloceras  taylori 106 

■  Species,  classified  list  of 15-18 

Specific  diflerences,  absence  of,  in  Placenticeras 196 

Sphenodiscidae '24, 56-83 

Sphenodiscus  Meek 39, 

51-57,  58, 83, 87, 91-95, 149, 163, 160, 180, 195, 233 

aeutodormtu$  Noetling 57 

acutum 58 

beecheriHyatt 69, 78-82, 264, S70 

helvidcrcnsis  var.  8erpe7Umus  Cragin 162. 164 

hclvideren^is  var.  udden  i  Cragin 159 

binckhorsti  Biihm .58. 82 

daMbll  Cragin 185 

cmarginatus  Cragin 157. 177 

isnuuliit  Zittel'. 58 

konincki  Hyatt 82,2?6 

lenticularis  (Owen) 57, 

58, 66, 70,  71-75, 77-82, 94, 95,  S68, 270 

var.  magniflcus 76 

var.  mississippiensis  Hyatt 77-78, 80, 81, 270 

var.  splendens  Hyatt 75-77. 79, 80, SOS 

lobatus  (Tuomey) ...  65, 66-70, 71, 75, 76, 80, 82, 264, 2«6, 470 

pleurisepta  (Conrad) 57, 

58,  59-65, 70, 71, 75, 82, 258,  g60. 262, 264 

requimi  Grossouvre 100 

rocmeri  Cragin 177 

rutoti  Grossouvre 83 

Siva  (Forbes) 88 

stantoni  Hyatt 70-7 1 ,  81, 362, 264 

iibagsbi  Grossouvre 82. 83 

Stepheoceras 102 

Stepheoceratidte 102 

Steuroccras  Cossman 105 

Stoliczkaia IW,  note;  137, 140, 141 

tetnigona  Neumayr Ill 

Styracoccras  Hyatt 83, 88, 244 

balduri  (Keyserling) 89. 244-245 

Subpulchellia  Hyatt 136, 137,  lSfl-140 

castellanensis  Hyatt 140. 2*." 

touquei  (NicklOs) 139 

oehlerti  (Sickles) 139 

sauvageaui  (Hermite) 139,140 

Subtisscitia  Hyatt 38, 42.  43. 45 

afrieana  (Peron) ■*■* 

inflata  (Peron) 43.45 

intermedia  (Peron) 43-44. 4.-» 

percmi  Hyatt ** 

Tachygcnesis 22. 23 

Tegoceras  Hyatt 83, 84 

mosense 84, 87 

Terminologv  employed 11-14 

Tissotia  Douvill^ 32,35,36,38,41,42,45,55,104,178 


INDEX. 


351 


Tissotia  DouvilM— Continued.  Page. 

(^ricana  Peron 44 

aure^ensis  Peron 49 

cossoni  Peron 64-55 

djelfensis  Peron 40 

ewaldi  ( von  Buch ) 44, 45, 46, 48 

Jicheu  ri  Grossouvre 51 

fourneli  Peron 36, 45, 49 

globosa  Hyatt 55 

grossou  vni  Peron 50 

haplopfiylta  Grossouvre 47, 48 

Ifevigala 44 

ri/bhii  Gros^onvre 4-1.  -16 


Tissotia  Douville— Continued.  Page. 

serrata 192 

slizcuiczi  Grosfouvre 49 

tkomasi  Peron 50, 55 

tissoti  (Bayle) 35, 36, 42, 43, 52 

Tissotiida-  Hyatt 24, 26, 30, 34, 35, 41-56, 84 

Tolypeceras  Hyatt 101,  note;  103-104 

marcousanum 103-104 

Traneceras 25 

Vascooeras  Choffat 101-102 

hartti  (Hyatt) 103,^50 

subconciliatum  Choffat 101 


o 


PUBLICATIONS  OF  UNITED  STATES  GEOLOGICAL  SURVEY. 

[Mon.ograph  XLIV.] 

The  serial  publications  of  the  United  States  Geological  Survey  consist  of  (1) 
Annual  Reports.  (-2)  Monographs,  (3)  Professional  Papers,  (-i)  Bulletins.  (5)  Mineral 
Resources,  (6)  Water-Supply  and  Irrigation  Papers,  (7)  Topographic  Atlas  of  the 
United  States — folios  and  separate  sheets  thereof,  (8)  Geologic  Atlas  of  the  United 
States — folios  thereof.  The  classes  numbered  2,  7,  and  S  are  sold  at  cost  of  publica- 
tion; the  others  are  distributed  free.  A  circular  giving  complete  lists  may  be  had 
on  application. 

MONOGRAPHS. 

I.   Lake  Bonneville,  by  (t.  K.  Gilbert.     1890.     4°.     xx,  438  pp.     .51  pi.     1   map.     Price  11.. W. 

(Out  of  stock.) 
II.  Tertiary  history  of  the  Grand  Canon  district,  with  atlas,  by  C.  E.  Button,  Capt.,  U.  S.  A. 
1882."  4°.     x'iv,  264  pp.     42  pi.  and  atla.s  of  24  sheets  folio!     Price  $10. 

III.  Geology  of  the  Coni.stock  lode  and  the  Washoe  district,  with  atlas,  by  G.  F.  Becker.     1882. 

4°.     XV,  422  pi>.     7  pi.  and  atlas  of  21  sheets  folio.     Price  $11. 

IV.  Comstock  mining  and  miners,  by  Eliot  Lord.     1883.     4°.     xiv,  451  pp.     3  pi.     Price  $1.. 50. 
V.  The  copper-bearing  rocks  of  Lake  .Superior,  by  R.  D.  Irving.     1883.     4°.     xvi,  464  pp.     15  1. 

29  pi.  and  maps.     Price  $1.85.     (Out  of  stock. ) 
VI.  Contributions  to  the  knowledge  of  the  older  Mesozoic  flora  of  Virginia,  by  W.M.Fontaine. 

1883.     4°.     xi,  144  pp.     54 1.     .54  pi.     Price  $1.05. 
VII.  Silver-lead  deposits  of  Eureka,  Nevada,  by  J.  S.  Curtis.     1884.     4°.     xiii,  200  pp.     16  pi. 
Price  $1.20. 
VIII.  Paleontology  of  the  Eureka  district,  by  C.  D.  Walcott.    1884.    4°.    xiii,  298  pp.    24  1.    24  pi. 
Price  $1.10. 
IX.  Brachiopoda  and  Lamellibranchiata  of  the  Raritan  clays  and  greensand  marls  of  New  Jersey, 
by  R.  P.  Whitfield.     188.5.     4°.     xx,  338  pp.     35  pi.     lump.     Price  $1.1.5. 
X.  Dinocerata.     A  monograph  of  an  extinct  order  of  gigantic  mammals,  by  O.  C.  Marsh.     1886. 
4°.     xviji,  243  pp.     .56  1.     56  pi.     Price  $2.70. 
XI.  Geological  history  of  Lake  Lahontan,  a  Quaternary  lake  of  northwestern  Nevada,  by  I.  C. 
Russell.     18.S5.     4°.     xiv,  288  pp.     46  pi.  and  maps.     Price  $1.75. 
XII.  <ieology  and  mining  industry  of  Leadville,  Colorado,  with  atlas,  by  S.  F.  EmuHms.     1886. 
4°.     xsix,  770  pp.     45  pi.  and  atlas  of  35  sheets  folio.     Price  $8.40. 

XIII.  (xefilogy  of  the  (juicksilver  deposits  of  the  Pacific  slope,  with  atlas,  by  G.  F.  Becker.     1888. 

4°.     xix,  486  jip.     7  pi.  and  atlas  of  14  sheets  folio.     Price  $2. 

XIV.  Fossil  fishes  and  fossil  plants  of  the  Triassic  rocks  of  New  Jersey  and  the  Connecticut  Valley, 

by  J.  S.  Newberry.     1888.     4°.     xiv,  1.52  pp.     26  pi.     Price  $1. 
XV.  The  Potomac  or  younger  Mesozoic  flora,  by  W.  M.  Fontaine.     1889.     4°.     xiv,  377  pp.     180 
pi.     Text  and  plates  bound  separately.     Price  $2.50. 
XVI.  The  Paleozoic  fishes  of  North  .America,  by  J.  S.  Newberry.     1889.     4°.     340   pp.     53   pi. 

Price  $1.00. 
XVII.  The  flora  of  the  Dakota  group,  a  po.sthumous  work,  by  Leo  Lesquereux.     Edited  by  F.  H. 
Knowlton.     1S91.     4°.     400  pp.     66  pi.     Price  $1.10. 
XVIIl.  GasterujiiMla  and  Cephalofioda  of  the  Raritan  clays  and  greensand  marls  of  New  Jersey,  by 
R.  P.  Whitfield.     1891.     4°.     402  pp.     .50  pi.     Price  $1. 
XIX.  The  Penokee  iron-bearing  series  of  northern  Wisconsin  and  Michigan,  by  R.  D.  Irving  and 
C.  R.  Van  Hise.     1892.     4°.     xix,  .5.34  jip.     Price  .$1.70. 
XX.  Geology  of  the  Eureka  district,  Nevada,  with  an  atlas,  by  Arnold  Hague.     1892.     4°.     xvii, 
419  pp.     8  pi.     Price  $.5.25. 
XXI.  The  Tertiary  rhynchophorous  Coleoptera  of  the  United  States,  by  S.  H.  Scudder.     1893.     4°. 
xi,  206  pp.     12  pi.     Price  90  cents. 
XXII    A  manual  of  topographic  methods,  by  Henry  Gannett,  chief  topographer.     1893.     4°.     xiv, 
300  pp.     18  pi.     Price  $1. 
XXIII.  Geology  of  the  Green  Mountains  in  Mas.sachusetts,  bv  Raphael  Pumpelly,  T.  N.  Dale,  and 
.L  E.  Wolff.     1894.     4°.     xiv,  206  pp.     23  pL     Price  $1.30. 

I 
MOX  .\LI\' — (K3 -J'd 


II 


PUBLICATIONS    OF    UNITED   STATES    GEOLOGICAL    SURVEY. 


XXIV. 

XXV. 

XXVI. 

XXVII. 

XXVIII. 

XXIX. 

XXX. 
XXXI. 

XXXII. 

XXXIII. 

XXXIV. 

XXXV. 

XXXVI. 

XXXVII. 

XXXVIII. 
XXXIX. 

XL. 

XLI. 

XLII. 

XLIII. 

XLIV. 


liy  R.  P.  Whitfield. 
38  pi.     Price 


MoUusca  and  Crustacea  of  the  Miocene  formations  of  Xew  Jer.«ev, 

1894.     4°.     \9;-\  pp.     24  pi.     Price  90  cent.s. 
The  Glacial  Lake  Agassiz,  bv  Warren  Uphaui.     1895.     4°.     xxiv,  658  pp. 

$1.70. 
Flora  of  the  Amboy  clays,  by  J.  S.  Newberrv;  a  posthumous  work,  eiiited  bv  Arthur 

Hollick.     1895.     4°.     260  pp.     58  pi.     Price  $1. 
Geology  of  the  Denver  Basin  in  Colorado,  bv  S.  F.  Emmons,  ^\'hitula^  Cross,  and  G.  H. 

Eldridge.     1896.     4°.     556  pp.     31  pi.     Price  $1..50. 
The  Marquette  iron-bearing  district  of  Michigan,  with  atlas,  by  C.  R.  Van  Hise  and  W.  S. 

Bayley,  including  a  chapter   on  the  Republic   trough,  by  H.  L.  Smyth.     1895.     4°. 

608  ijp.     35  pi.  and  atlas  of  39  sheets  folio.     Price  $5.75. 
Geology  of  old  Hampshire  Countv.  Massachusetts,  comprising  Franklin,  Hampshire,  and 

Hampden  counties,  liv  B.  K.  Emerson.     1898.     4°.     xxi,  790  pp.     35  \>\.     Price  $1.90. 
Fossil  Medusa-,  by  C.  D.  Walcott.     1898.     4°.     ix,  201  pp.     47  pi.     Price  $1.50. 
Geology  of  the  As])en  mining  district,  Colorado,  with  atlas,  by  J.  E.  S])urr.     1898.     4°. 

XXXV,  260  pp.     43  pi.  and  atlas  of  30  sheets  folio.     Price  S3. 60. 
Geology  of  the  Yellowstone  National  Park,  Part  II,  descrijjtive  geology,  petrography,  and 

paleontology,  bv  Arnold  Hague,  J.  P.  Iddings,  W.  H.  Weed,  C.  D.  Walcott,  G.  H.  Girtv. 

T.  W.  Stanton,  and  F.  H.  Knowlton.     1899.     4°.     x\di,  893  pp.     121  pi.     Price  .S2.45. 
Geology  of  the  Narragansett  Basin,  by  N.  S.  Shaler,  J.  B.  Woodworth,  and  A.  F.  Foerste. 

1899.'    4°.     XX,  402  pp.     31  pi.     Price  ?1. 
The  glacial  gravels  of  Maine  and  their  associated  deposits,  bv  G.  H.  Stone.     1899.     4°. 

xiii,  499  pp.     52  pi.     Price  SI. .30. 
The  later  extinct  floras  of  North  America,  by  J.  S.  Newberrv:  edited  bv  Arthur  Hollick. 

1898.     4°.     xviii,  295  pp.     68  pi.     Price  SI. 25. 
The  Crystal   Falls   iron-liearing  district  of   Michigan,  by  J.   M.  Clements  and   H.   L. 

Smyth;  with  a  chapter  on  the  Sturgeon  River  tongue,  by  W.  S.  Bavlev,  and  an  intro- 
duction by  C.  R.  Van  Hise.     1899.     4°.     sxxvi,  512  pp.  "  53  pi.     Price" S2. 
Fossil  flora  of  the  Lower  Coal  Measures  of  Missouri,  by  David  White.     1899.     4°.     xi,  467 

pp.     73  pi.     Price  81.25. 
The  lUinois  glacial  lobe,  by  Frank  Leverett.     1899.     4°.     xxi,  817  pp.    24  pi.    Price  SI. 60. 
The  Eocene  and  Lower  Gligocene  coral  faunas  of  the  L'nited  States,  with  descriptions  of 

a  few  doubtfully  Cretaceous  species,  bv  T.  W.  Vaughan.     1900.     4°.     263  pp.     24  pi. 

Price  SI.  10. 
Ade|ihagous  and  clavicorn  Coleoptera  from  the  Tertiary  deposits  at  Florissant,  Colorado, 

with  descriptions  of  a  few  other  forms  and  a  systematic  list  of  the  non-rhyncophorous 

Tertiary  Coleoptera  of  North  America,  by  S.  H.  Scudder.     1900.     4°.     148  pp.     11  pis. 

Price  80  cents. 
Gilacial  formations  and  drainage  features  of  the  Erie  and  Ohio  basins,  by  Frank  Leverett. 

1902.     4°.     802  pp.     26  pis.     Price  81.75. 
Carboniferous   ammonoids  of   America,   by  J.  P.  Smith.     1903.      4°.     211  pp.     29  pis. 

Price  S5  cents. 
The  IMesabi  iron-bearing  district  of  ^linnesota,  by  C.  K.  Leith.     1903.     4°.     316  pp.     33 

pis.     Price  81.50. 
Pseudoceratites  of  the  Cretaceous,  bv  Alpheus  Hyatt,  edited  by  T.  \V.  Stanton.     1903. 

4°.     351  pp.     47  pis.     Price  81.00.  ' 

All  remittances  must  be  by  money  order,  made  payable  to  the  Director  of  the 
United  States  Geological  Survey,  or  in  currency — the  exact  amount.  Checks,  drafts, 
and  postage  stamps  can  not  be  accepted.     Correspondence  should  be  addressed  to 

The  Director. 

United  States  Geological  Survey. 

Washington,  D.  C. 
May,  190.3. 


